erros x = 1 is not a root and 2nd loop solved is wrongly done. . . To master your problem-solving skills up to JEE Advanced join our course jeesimplified.com/set-of-60 . Send us the hardest question solved by you forms.gle/HZxgUAKdWV1Pywgb8
Pehle hi bata du fekne me muze koi interest nahi hai ... jee main 2024 30 jan shift 1 99.91pr hai mera ......Bolte hue bura to lag rha hai bavjood ki me khood bohot achha feel karunga agar koi meri baat samjega ... i know it is difficult to provide such amazing content free on yt but in previous time bhai aapne vo chiz provide karai thi .. aap apne set of 60 ke behtarine sawal late the yaha pe .. magar ab nahi late .. jo bhi reason ho magar aap wo content nahi to us level ka content plz provide karate rahie ....ha ese method kaam ke hai magar pura paper method wale ese qn ka to sirf calculation me use karenge na ki qn ki thought process me jo aap purane qn me build karvate the 😢😊😊
Another way i solved it in: Let y=√(5-x). Let us find its inverse function. We see that the inverse of √(5-x) is 5-x^2 !!! So the solutions to √(5-x)=5-x^2 will be on the line y=x (since inverses are reflections about y=x, their intersections will lie on y=x) hence we can equate 5-x^2=x giving us x^2+x-5=0 giving us x= (-1±√(21))/2
Bro there are four solutions in my opinion (because I haven't seen the video) x = (-1±√(21))/2 and (1±√(17))/2. I did it taking 5 to be variable and x to be constant then I solved it.
My method, (5-x)^1/2 = 5 - x + x -x^2 Now taking 5 - x on left side and taking( 5-x)^1/2 as common (5-x)^1/2 [ 1 - (5-x)^1/2] = x [ 1 - x] Now if we compare both sides we can equate (5-x)^1/2 with x And then after squaring both sides we get the required quadratic which is x^2 + x - 5 = 0.......and applying quadratic formula to get roots
10:40 the value can be substitued in the original eqn which was 5-x= (5-x^2)^2 , we would get the value of x that are the soln , and also if we sketch graphs of root(5-x) and 5-x^2 , we will get only two intersection thus only two ans.....
I solved it as an intersection of 2 parabolas. y² = 5-x and (only top part) and x²=5-y. Now if we subtract the two we will get y²-x²=y-x so either y+x-1 = 0 or y-x=0. Now we can put these cases and solve for 4 roots then check for which values y is +ve (as we are only considering the upper segment of y²=5-x)
it is also worth noting that the parabolas are inverse of each other and then by graph we can easily notice that y+x-1=0 or x=y and then we can proceed with your solution... it felt amazing coming up with this solution
I solved it in like 3 mins with a completely different approach: sqrt (5-x)=5-x^2=y (let) Then, the two equations can become: y=sqrt (5-x) or x+y^2=5 And, y= 5-x^2 or x^2+y=5 Hence, equating the two equations, x^2+y= x+y^2 x^2-y^2 - (x-y)=0 (X+y)(x-y) - (x-y)=0 (X-y)(x+y-1)=0 This gives either x=y or y=1-x (i) x=y in first eqn: x^2+x=0-> solve to get two solutions (ii) y=1-x-> x^2+(1-x)=5 or x^2-x-4=0-> solve to get two more solutions.
Solve for x over the real numbers: sqrt(-x + 5) - (-x^2 + 5) = 0 sqrt(-x + 5) - (-x^2 + 5) = -5 + x^2 + sqrt(-x + 5): -5 + x^2 + sqrt(-x + 5) = 0 Subtract x^2 - 5 from both sides: sqrt(-x + 5) = -x^2 + 5 Raise both sides to the power of two: -x + 5 = (-x^2 + 5)^2 Expand out terms of the right hand side: -x + 5 = x^4 - 10 x^2 + 25 Subtract x^4 - 10 x^2 + 25 from both sides: -x^4 + 10 x^2 - x - 20 = 0 The left hand side factors into a product with three terms: -(x^2 - x - 4) (x^2 + x - 5) = 0 Multiply both sides by -1: (x^2 - x - 4) (x^2 + x - 5) = 0 Split into two equations: x^2 - x - 4 = 0 or x^2 + x - 5 = 0 Add 4 to both sides: x^2 - x = 4 or x^2 + x - 5 = 0 Add 1/4 to both sides: x^2 - x + 1/4 = 17/4 or x^2 + x - 5 = 0 Write the left hand side as a square: (x - 1/2)^2 = 17/4 or x^2 + x - 5 = 0 Take the square root of both sides: x - 1/2 = sqrt(17)/2 or x - 1/2 = -sqrt(17)/2 or x^2 + x - 5 = 0 Add 1/2 to both sides: x = 1/2 + sqrt(17)/2 or x - 1/2 = -sqrt(17)/2 or x^2 + x - 5 = 0 Add 1/2 to both sides: x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x^2 + x - 5 = 0 Add 5 to both sides: x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x^2 + x = 5 Add 1/4 to both sides: x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x^2 + x + 1/4 = 21/4 Write the left hand side as a square: x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or (x + 1/2)^2 = 21/4 Take the square root of both sides: x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x + 1/2 = sqrt(21)/2 or x + 1/2 = -sqrt(21)/2 Subtract 1/2 from both sides: x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x = sqrt(21)/2 - 1/2 or x + 1/2 = -sqrt(21)/2 Subtract 1/2 from both sides: x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x = sqrt(21)/2 - 1/2 or x = -1/2 - sqrt(21)/2 sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (1/2 - sqrt(17)/2)) - (5 - (1/2 - sqrt(17)/2)^2) = 1/2 (-1 - sqrt(17) + sqrt(2 (sqrt(17) + 9))) ≈ 0: So this solution is correct sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (sqrt(17)/2 + 1/2)) - (5 - (sqrt(17)/2 + 1/2)^2) = -5 + sqrt(9/2 - (sqrt(17))/2) + (sqrt(17)/2 + 1/2)^2 ≈ 3.12311: So this solution is incorrect sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (-sqrt(21)/2 - 1/2)) - (5 - (-sqrt(21)/2 - 1/2)^2) = 1/2 (1 + sqrt(21) + sqrt(2 (sqrt(21) + 11))) ≈ 5.58258: So this solution is incorrect sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (sqrt(21)/2 - 1/2)) - (5 - (sqrt(21)/2 - 1/2)^2) = -5 + sqrt(11/2 - (sqrt(21))/2) + (sqrt(21)/2 - 1/2)^2 ≈ 0: So this solution is correct The solutions are: Answer: | | x = 1/2 - sqrt(17)/2 or x = sqrt(21)/2 - 1/2
This question was actually designed/made to solve after realizing that the given is one and only f(x) = f¯¹(x) and we have to solve f(x)=x to get to our solution... But still there's a catch here, after solving via this method we'll end up in only one root, so for the other root we'll have to observe some critical points from graph of both fns and then we will get to know that the other root (-ve one) will actually lie on a line with slope - 1 and it's y intercept will come out to be the sum of x and y coordinates... After this we can solve directly by equating both the eqns and we will easily get the sum of coordinates of x, y to be 1 hence we will get our line and after that is our standard approach.... Also for rejecting 2 solns in your soln bhaiya we will use graphical approach and there we will be having 2 roots one negative one positive Edit : I solved in about 5mins Also I knew your approach bhaiya, but didn't went through it because it was long(for me atleast)
@@Mathlover_1729 I also thought the same before my method but I then I realized that no we cannot solve it by assigning x to trignomentric ratio... Since sin cos cosec and sec ratios are either bounded or does not have real range, because we don't know whether x will be having solutions less than 1 or greater than 1 same goes for - 1.... We can surely put x to some tan@ or cot@ and solve since then it will solve for all real x... I hope I was able to clarify it
The moment your wire 5^2 and 5 separately I knew this was like a wierd thing I did when I was in 10th, I was doing rd sharma when this idea struck me, i was like what if there is a quadratic in constant not a variable, I even made and tried a few questions and they were right I verified , but I saw no use of it at that time it felt like discovering Maths at that time, I even felt discussing with my father who is a maths teacher till 10 th but i thought this is maybe just a wierd thing, by chnace it worked maybe or something like that and then jee prep but now seeing your video reminded me of that instantly... It's literally a very nice and wierd approach
After I got x²+x-5 as one factor, in the quartic equation i just divided it by the factor and got both quadratics and solved them😅 , couldn't think of your method before the video unfortunately, however we got 2 extra roots by squaring on both sides but the square root doesn't give both ± so -√5≤ x ≤√5 , I removed extraneous solutions by putting it in the orginal equation 👍
so first i graphed both the functions to check the number of real solutions, they intersected at 2 point (1 +ve & 1 -ve). Now i started solving the sum, i took the x^2 term to the other side (x^2 = 5 - (5-x)^1/2) now sbs we get x = +- ( 5 - (5-x)^1/2)^1/2 now we plug in the value of x in this equation and get a infinite loop of -ve square root of 5 now assume that to be x sbs get a quadratic and we got the positive root now we can use -part of x [-(5-(5-x)^1/2] to get our other solution in a similar way but this time we will get alternate +ve and -ve square root of five in our loop.
one of the easiest approcach and in very less steps is: root(5-x) = 5- x^2 rearranging x^2 = 5 - root(5-x) taking root both sides x = root( 5 - root(5-x)) and we can replace x in RHS by the value of x from the LHS, so then x = root(5-root(5-root(5-x))) and repeat so on, and if we look reverse way then, x= root(5-x), then squaring both sides then we get x^2 = 5-x, and hence we have solved this SO CALLED AMAZING EQUATION by PATTERN
we can solve by solving graph of 2 parabolas where both parabolas are symmetric about y=x hence the in tersecting point y=x so this is method using graphs
I was able to solve the Q with same approach because of the hint given in the thumbnail 😌 And to eliminate extra values we can put them in original equation and discard the values at which we are getting negativite value inside the sq. root .
Ye achhi community h doston...time agr h 2 saal acche se to follow krna..agr last 3 4 months me ho to follow pyqs only and modules of your coaching.. AIR 1789 (JEE 2022) here
WE can eliminate the values based on the domain of x we get . 5-X is under square root thus x must be less than 0 and 5-x^2 must be more than or equal to 0. So we get x must lie between ..... negative root 5 to root 5 . So we are done.
graphical method has always been best. plot both the graphs and since they are inverse of each other, one or more root lies on y=x 5-x^2=y=x (first quadratic)or √(5-x)=y=x
Another method i tried: subtracting x from both sides √(5-x)-x=5-x^2-x rationalizing both sides [√(5-x)-x][√(5-x)+x]/[√(5-x)+x]=5-x^2-x simplifying the numerator [5-x^2-x]/[√(5-x)+x]=5-x^2-x Cancelling out Numerator of LHS and RHS ( noting that we have a solution where 5-x^2-x =0)[quadratic no.1] [√(5-x)+x]=1 bring x on rhs and now you can solve the quadratic no.2
another easy and quick method: let under root 5-x be y hence y squared = 5-x so x=5 - y squared. let this be equation 1 5 - x square is also y. y= 5 - x square. let this be equation 2 so equation 1- equation 2 will be x square - y square = x - y so either x=y or x=-y putting y=x in equation 1, we get x=5-x square. this is quadratic and can be solved putting y=-x in equation 2, we get y square= 5+ y. we can solve for y and hence get x becuase x=-y
i was able to think by substituting y assuming y = sq.rt of 5-x. Thinking to relate it as parabola and Quadratic graph the only essence that the graph rotated. So able to guess x=y.
Here’s a way to solve the initial equation obtained of 4th degree: X^4 - 10X^2 + X + 20 = 0 Factorising the 4th degree expression into two quadratics: Let, X^4 - 10X^2 + X + 20 = (X^2 + AX + B)*(X^2 + CX + D) Comparing coefficients of X^3 in LHS and RHS, C+ A = 0 or C = -A Comparing coefficients of X^2 , D+ AC + B = -10 and because C = -A, hence D- A^2+ B = -10 -(1) Comparing coefficients of X, AD + BC = 1 and because C = -A, AD - AB = 1 or A(D-B)=1 -(2) Lastly comparing constant terms, BD= 20 - (3) Trying for integral solutions to (3), we obtain B = -4 and D = -5 (by checking divisors of 20) Putting B = -4 and D = -5 in (2), We get A = -1 Now it remains to check if these values satisfy (1) LHS = D- A^2+ B = [-5] - [1] + [-4] = -10 = RHS. Therefore, A = -1 B = -4 D = -5 And C = -A = 1 Hence, the original 4th degree expression can be factorised as X^4 - 10X^2 + X + 20 = (X^2 - X - 4)(X^2 + X - 5) Now to find the roots, (X^2 - X - 4)(X^2 + X - 5) = 0 The roots obtained are [1 (+-) sqrt(17)]/ 2 and [-1 (+-) sqrt(21)]/ 2 As the domain of the function can be found to be [-sqrt(5), +sqrt(5)] The acceptable values of roots are 1/2*[1-sqrt(17)] and 1/2*[-1 + sqrt (21)] QED. This is not a general method, but often works for depressed quartics.
X= (-1±√21) /2, given expression equates a function with its inverse, and we know that a function and it's inverse always meet at line y=x, therefore we can equate 5-x^2 with x to obtain the ans, but we have to check that whether they satisfy the condition and on checking we will obtain our final ans as X=(-1+√21) /2
Thanks bhaiya for taking my suggested question. Ye question Maine ek bade achhe channel se liya tha, jiska naam hai "BlackPenRedPen". Us channel pe high school maths se high level maths ke achhe question mil jaate hain. Ye mujhe vahine se mila tha. I'll recommend everyone to checkout that channel also👍
another method we can do is creating prefect squares ....shift root(5-x) to the right add and subtract x we will see formation of 2 perfect squares {root(5-x)^2 - 1/2}^2 = (x- 1/2)^2 ...now we can easily solve these equations as it will reduce into 2 quadratic equations..😁
5 ko variable ki tarah treat kiya aur x aur uske saare terms ko contsants bana diya. Aur uske solutions use karke x ki values bata di. x = (-1±√(21))/2 or x=(1±√(17))/2
Its almost wondeful to see people solve such beautiful equations, i saw this same equation 5 years ago on a channel black pen red pen. (Dear tejas i solved it or something like that was the title). Amazing to see this questions again after so long.
Bolte hue bura to lag rha hai bavjood ki me khood bohot achha feel karunga agar koi meri baat samjega ... i know it is difficult to provide such amazing content free on yt but in previous time bhai aapne vo chiz provide karai thi .. aap apne set of 60 ke behtarine sawal late the yaha pe .. magar ab nahi late .. jo bhi reason ho magar aap wo content nahi to us level ka content plz provide karate rahie ....ha ese method kaam ke hai magar pura paper method wale ese qn ka to sirf calculation me use karenge na ki qn ki thought process me jo aap purane qn me build karvate the 😢😊😊
X=(1+√17)/2 lene pe original equation me put krne pe RHS -ve arha h jo ki nhi hoskta because under root of positive known quantity is always positive so aise ek case eliminate horha h , baki 2nd nhi click kra
This question can become more easy tell me my method is right or wrong according to the method √ 5 - x is equal to 5 minus x square root 5 is equal to 5 minus x square + x here 5 minus x square + X is and quadratic equation find the value of x using the quadratic formula we got the answer that x is equal to minus 1 + root 21 upon 2 which is the answer
Hi bhaiya I am also a jee aspirant aur maine aapka channel shorts pe bahut dekha h aur thank you for giving itne sahi question kuch kuch toh easy lgte h but kuch mein aisi band bajti h but thank you Also main ek request kr rha hu ki please agr ho ske toh aap vaapis vo problem solving ki videos of every chapter lao na 😊 vo bahut acchi series thi please agr ho ske toh please laiye
maine ye socha ki pehle squaring karle and then quadratic jo ban rhi usko solve alag kare and =x^4 kar de then x^4 ko x^2x^2 karke jo factors bne the qudaratic ke usse equate akre to same a jayega at 9:24
Bro when pointed out that it’s quadratic of five then it ringed very well thought loved it may be I can get types of question related to this that will be fun . Anyhow I enjoyed the solution very much it’s not everyday u get some nice ideas when solving
Ek doubt hai bhai aapne jo yha per 3:16 x ko liya aise to hum Ramanujan submition ka solution laate hai but wo wrong approach bataya jata hai to yha sahi kaise ho jata hai
Bhaiya ! I did thus que by geetting two parabolas and plotting them under the domain -✓5 to ✓5 (i saw one more guy with thus approach but he may get more roots is not considering the x domain) x°2-y^2=x-y so[ x-y =0] or [x+y=1] Thanks
erros
x = 1 is not a root and 2nd loop solved is wrongly done.
.
.
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@@puchokaun error likhne me bhi error ho gyi bhai se 😂
😅 yeah I have seen this
@@yuraje4k348 toh kya bhai? hota hai insaan hai wo bhi
Pehle hi bata du fekne me muze koi interest nahi hai ... jee main 2024 30 jan shift 1 99.91pr hai mera ......Bolte hue bura to lag rha hai bavjood ki me khood bohot achha feel karunga agar koi meri baat samjega ... i know it is difficult to provide such amazing content free on yt but in previous time bhai aapne vo chiz provide karai thi .. aap apne set of 60 ke behtarine sawal late the yaha pe .. magar ab nahi late .. jo bhi reason ho magar aap wo content nahi to us level ka content plz provide karate rahie ....ha ese method kaam ke hai magar pura paper method wale ese qn ka to sirf calculation me use karenge na ki qn ki thought process me jo aap purane qn me build karvate the 😢😊😊
Another way i solved it in:
Let y=√(5-x). Let us find its inverse function. We see that the inverse of √(5-x) is 5-x^2 !!!
So the solutions to √(5-x)=5-x^2 will be on the line y=x (since inverses are reflections about y=x, their intersections will lie on y=x) hence we can equate 5-x^2=x giving us x^2+x-5=0 giving us x= (-1±√(21))/2
I did it by this method, but these functions are inverses only for x>0. You'd have to find the other solution by some different method.
I think im only to do like this 😂
Bro there are four solutions in my opinion (because I haven't seen the video) x = (-1±√(21))/2 and (1±√(17))/2.
I did it taking 5 to be variable and x to be constant then I solved it.
This doesn’t always work.
@@ryanrahuelvalentine2879 oh really
My method,
(5-x)^1/2 = 5 - x + x -x^2
Now taking 5 - x on left side and taking( 5-x)^1/2 as common
(5-x)^1/2 [ 1 - (5-x)^1/2] = x [ 1 - x]
Now if we compare both sides we can equate (5-x)^1/2 with x
And then after squaring both sides we get the required quadratic which is
x^2 + x - 5 = 0.......and applying quadratic formula to get roots
I did with same method
10:40 the value can be substitued in the original eqn which was 5-x= (5-x^2)^2 , we would get the value of x that are the soln , and also if we sketch graphs of root(5-x) and 5-x^2 , we will get only two intersection thus only two ans.....
I solved it as an intersection of 2 parabolas. y² = 5-x and (only top part) and x²=5-y. Now if we subtract the two we will get y²-x²=y-x so either y+x-1 = 0 or y-x=0. Now we can put these cases and solve for 4 roots then check for which values y is +ve (as we are only considering the upper segment of y²=5-x)
We have to consider this( -✓5,✓5)domain to
Thats correct but must be time consuming
it is also worth noting that the parabolas are inverse of each other and then by graph we can easily notice that y+x-1=0 or x=y and then we can proceed with your solution... it felt amazing coming up with this solution
Copied straight from blackpen red pen 😮
I see a man of culture here
Can you give me the link of video
Haan Bhai, vahine se Diya tha maine😊, khud to itne badiya sawal nahi bana sakta na😅
@@adityaagarwal636hello aap ne hi ye sawal bhaiya ko Diya tha
@@UmG_Editzhaan bhai
Reminds me of that problem in "pair of straight lines", applying the concept of homogenization of a curve, taking 1 as a variable.
Yeah man
that memory... Insane
7:04 Understood, we have make a quadratic taking 5 as a variable and finding it's value in terms of x.....❤
I solved it in like 3 mins with a completely different approach:
sqrt (5-x)=5-x^2=y (let)
Then, the two equations can become:
y=sqrt (5-x) or x+y^2=5
And, y= 5-x^2 or x^2+y=5
Hence, equating the two equations,
x^2+y= x+y^2
x^2-y^2 - (x-y)=0
(X+y)(x-y) - (x-y)=0
(X-y)(x+y-1)=0
This gives either x=y or y=1-x
(i) x=y in first eqn: x^2+x=0-> solve to get two solutions
(ii) y=1-x-> x^2+(1-x)=5 or x^2-x-4=0-> solve to get two more solutions.
👍👍👍👍👍
Nice😊
i) =5 ✓ not =0
Acha community h bhoi log....
JEE Adv 2016 rank 5574 here❤
Hello bhaiya can u please guide me I just moved to 12
Aise comment ke nhi hoga ache se guide..bhaiya ka paid mentorship le le @AbhishekRaj
@@iitiandev121 bhaiya wo jyada ho jayega abhi utna afford nhi kr skta
Konse iit m ho bhaiya
@@reviewer3562 Tanishq rajak?
X = 1 kaam kaise kr rha hai ? Check kro equation me x = 1 daalke
Bhai 2 min tak pagal ho raha tha ki x=1 kaam kaise kar raha hai
Mujhe laga mai maths bhul gaya
@@prince-hb8qk same 💀
Exactly
Bhai nasha karna band krde
Same
1:28 apply rational root theorem agar sare zeros irrational and complex nhi h to work krega
10:41 cases orignal eq se eliminate ho jayenge since x² is less than 5 therefore x would be approx less than 2.23🙂
Solve for x over the real numbers:
sqrt(-x + 5) - (-x^2 + 5) = 0
sqrt(-x + 5) - (-x^2 + 5) = -5 + x^2 + sqrt(-x + 5):
-5 + x^2 + sqrt(-x + 5) = 0
Subtract x^2 - 5 from both sides:
sqrt(-x + 5) = -x^2 + 5
Raise both sides to the power of two:
-x + 5 = (-x^2 + 5)^2
Expand out terms of the right hand side:
-x + 5 = x^4 - 10 x^2 + 25
Subtract x^4 - 10 x^2 + 25 from both sides:
-x^4 + 10 x^2 - x - 20 = 0
The left hand side factors into a product with three terms:
-(x^2 - x - 4) (x^2 + x - 5) = 0
Multiply both sides by -1:
(x^2 - x - 4) (x^2 + x - 5) = 0
Split into two equations:
x^2 - x - 4 = 0 or x^2 + x - 5 = 0
Add 4 to both sides:
x^2 - x = 4 or x^2 + x - 5 = 0
Add 1/4 to both sides:
x^2 - x + 1/4 = 17/4 or x^2 + x - 5 = 0
Write the left hand side as a square:
(x - 1/2)^2 = 17/4 or x^2 + x - 5 = 0
Take the square root of both sides:
x - 1/2 = sqrt(17)/2 or x - 1/2 = -sqrt(17)/2 or x^2 + x - 5 = 0
Add 1/2 to both sides:
x = 1/2 + sqrt(17)/2 or x - 1/2 = -sqrt(17)/2 or x^2 + x - 5 = 0
Add 1/2 to both sides:
x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x^2 + x - 5 = 0
Add 5 to both sides:
x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x^2 + x = 5
Add 1/4 to both sides:
x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x^2 + x + 1/4 = 21/4
Write the left hand side as a square:
x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or (x + 1/2)^2 = 21/4
Take the square root of both sides:
x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x + 1/2 = sqrt(21)/2 or x + 1/2 = -sqrt(21)/2
Subtract 1/2 from both sides:
x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x = sqrt(21)/2 - 1/2 or x + 1/2 = -sqrt(21)/2
Subtract 1/2 from both sides:
x = 1/2 + sqrt(17)/2 or x = 1/2 - sqrt(17)/2 or x = sqrt(21)/2 - 1/2 or x = -1/2 - sqrt(21)/2
sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (1/2 - sqrt(17)/2)) - (5 - (1/2 - sqrt(17)/2)^2) = 1/2 (-1 - sqrt(17) + sqrt(2 (sqrt(17) + 9))) ≈ 0:
So this solution is correct
sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (sqrt(17)/2 + 1/2)) - (5 - (sqrt(17)/2 + 1/2)^2) = -5 + sqrt(9/2 - (sqrt(17))/2) + (sqrt(17)/2 + 1/2)^2 ≈ 3.12311:
So this solution is incorrect
sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (-sqrt(21)/2 - 1/2)) - (5 - (-sqrt(21)/2 - 1/2)^2) = 1/2 (1 + sqrt(21) + sqrt(2 (sqrt(21) + 11))) ≈ 5.58258:
So this solution is incorrect
sqrt(-x + 5) - (-x^2 + 5) ⇒ sqrt(5 - (sqrt(21)/2 - 1/2)) - (5 - (sqrt(21)/2 - 1/2)^2) = -5 + sqrt(11/2 - (sqrt(21))/2) + (sqrt(21)/2 - 1/2)^2 ≈ 0:
So this solution is correct
The solutions are:
Answer: |
| x = 1/2 - sqrt(17)/2 or x = sqrt(21)/2 - 1/2
😮😮😮😮😮😮😮😮😮🎉🎉🎉🎉🎉❤❤❤❤❤❤❤❤❤😮😮😮😮😮😮❤❤❤
This question was actually designed/made to solve after realizing that the given is one and only f(x) = f¯¹(x) and we have to solve f(x)=x to get to our solution... But still there's a catch here, after solving via this method we'll end up in only one root, so for the other root we'll have to observe some critical points from graph of both fns and then we will get to know that the other root (-ve one) will actually lie on a line with slope - 1 and it's y intercept will come out to be the sum of x and y coordinates... After this we can solve directly by equating both the eqns and we will easily get the sum of coordinates of x, y to be 1 hence we will get our line and after that is our standard approach.... Also for rejecting 2 solns in your soln bhaiya we will use graphical approach and there we will be having 2 roots one negative one positive
Edit : I solved in about 5mins
Also I knew your approach bhaiya, but didn't went through it because it was long(for me atleast)
Nice approach bro... But can we not solve by putting x=5cosΩ Ω€[-π/2,π/2] ... My process is short
@@Mathlover_1729 I also thought the same before my method but I then I realized that no we cannot solve it by assigning x to trignomentric ratio... Since sin cos cosec and sec ratios are either bounded or does not have real range, because we don't know whether x will be having solutions less than 1 or greater than 1 same goes for - 1.... We can surely put x to some tan@ or cot@ and solve since then it will solve for all real x... I hope I was able to clarify it
After finding 1st two roots by putting y=x we can square original equation and divide it by eqn having two roots we got earlier
@@ParthBnsl-iitis yes bro,this is the problem
X=1 toh root hai hee nahi?Factor kese kar diya uska
The moment your wire 5^2 and 5 separately I knew this was like a wierd thing I did when I was in 10th, I was doing rd sharma when this idea struck me, i was like what if there is a quadratic in constant not a variable, I even made and tried a few questions and they were right I verified , but I saw no use of it at that time it felt like discovering Maths at that time, I even felt discussing with my father who is a maths teacher till 10 th but i thought this is maybe just a wierd thing, by chnace it worked maybe or something like that and then jee prep but now seeing your video reminded me of that instantly... It's literally a very nice and wierd approach
Are gajab
Eise sochna bhi ho skaata
Q chota sa hn par Eise karke kai equation mein apply kar sakenge
Thanks Bhaiya ji
After I got x²+x-5 as one factor, in the quartic equation i just divided it by the factor and got both quadratics and solved them😅 , couldn't think of your method before the video unfortunately, however we got 2 extra roots by squaring on both sides but the square root doesn't give both ± so -√5≤ x ≤√5 , I removed extraneous solutions by putting it in the orginal equation 👍
so first i graphed both the functions to check the number of real solutions, they intersected at 2 point (1 +ve & 1 -ve). Now i started solving the sum, i took the x^2 term to the other side (x^2 = 5 - (5-x)^1/2) now sbs we get x = +- ( 5 - (5-x)^1/2)^1/2 now we plug in the value of x in this equation and get a infinite loop of -ve square root of 5 now assume that to be x sbs get a quadratic and we got the positive root now we can use -part of x [-(5-(5-x)^1/2] to get our other solution in a similar way but this time we will get alternate +ve and -ve square root of five in our loop.
Bhai , baaki videos nhi kroge upload?
Lovely sol. bro
Congrats on completing the challenge.💯
one of the easiest approcach and in very less steps is:
root(5-x) = 5- x^2
rearranging x^2 = 5 - root(5-x)
taking root both sides
x = root( 5 - root(5-x))
and we can replace x in RHS by the value of x from the LHS,
so then x = root(5-root(5-root(5-x))) and repeat so on,
and if we look reverse way then,
x= root(5-x), then squaring both sides
then we get x^2 = 5-x, and hence we have solved this SO CALLED AMAZING EQUATION by PATTERN
we can solve by solving graph of 2 parabolas where both parabolas are symmetric about y=x hence the in tersecting point y=x so this is method using graphs
Actually, root(17) +1/2 won’t be the solutions as they don’t satisfy the original equation. They are extra solutions obtained from squaring.
10;19 root ke andar sq. Hai toh mod se khulega aur do case banege ....jinhe solve karte hi ek ek eliminate ho jaenge because of mod ki condition
I was able to solve the Q with same approach because of the hint given in the thumbnail 😌
And to eliminate extra values we can put them in original equation and discard the values at which we are getting negativite value inside the sq. root .
7:10 pe pata hai 5=shree dharacharya expression in x likhoge as given in title of video , i used to do shxt like this alot good its gettin traction
Ye achhi community h doston...time agr h 2 saal acche se to follow krna..agr last 3 4 months me ho to follow pyqs only and modules of your coaching..
AIR 1789 (JEE 2022) here
It should be+10x^2
haaa bhaiya main hi hi 1/ plancks constant sec me banane wala
its plancks constant
Woh kiya hota hai?
😂😂😂🤣@@noexistence88
Plancks constant h ~ 10^-34
1/h~ 10^34
10^34 seconds means 10^26 years !!
Think once....
bhaisab, tum J^-1s^-1 mei banate ho question? Kya logic hai.
WE can eliminate the values based on the domain of x we get . 5-X is under square root thus x must be less than 0 and 5-x^2 must be more than or equal to 0. So we get x must lie between ..... negative root 5 to root 5 . So we are done.
7:09 Assuming a quadratic in 5
One doubt. Agar quadratic 5 me banali humne then sum of roots and product of roots kiske equal hoga?🤔🤨
Equal roots ka case hai dono root 5 hi hai
x = ✓(5-x)
divide both sides by, ✓(5-x)
x/(✓(5-x)) = 1
rationalize to get,
x(✓(5-x)) /(5 - x) = 1
square both sides to get,
(x^2)(5-x)/(5-x)^2 = 1
(x^2)/(5-x) = 1
x^2 = 5-x (by multiplying 5-x to both sides)
now, get the quadratic equation,
x^2+x-5 = 0
finally solve the quadratic
drawing graphs of both the function simultaneously can give no of solution. For value your method is great
graphical method has always been best.
plot both the graphs and since they are inverse of each other, one or more root lies on y=x
5-x^2=y=x (first quadratic)or √(5-x)=y=x
√5-x = 5-x²
Squaring both sides
5-x=25+x⁴-10x²
fir, ab solve karte baith polynomial
bhai new vids kab aaegi
10:19 if we will not then root ke andar -ve aa jya ga?
I have solved such question on bhannat maths channel in which he habe given cubic so it was eazy for me
7:20 quadratic in 5
Another method i tried:
subtracting x from both sides
√(5-x)-x=5-x^2-x
rationalizing both sides
[√(5-x)-x][√(5-x)+x]/[√(5-x)+x]=5-x^2-x
simplifying the numerator
[5-x^2-x]/[√(5-x)+x]=5-x^2-x
Cancelling out Numerator of LHS and RHS ( noting that we have a solution where 5-x^2-x =0)[quadratic no.1]
[√(5-x)+x]=1
bring x on rhs and now you can solve the quadratic no.2
Where are other 2 solutions...
That's the only problem about this method...
Be aware next time !!!
another easy and quick method:
let under root 5-x be y
hence y squared = 5-x
so x=5 - y squared. let this be equation 1
5 - x square is also y.
y= 5 - x square. let this be equation 2
so equation 1- equation 2 will be
x square - y square = x - y
so either x=y or x=-y
putting y=x in equation 1, we get x=5-x square. this is quadratic and can be solved
putting y=-x in equation 2, we get y square= 5+ y. we can solve for y and hence get x becuase x=-y
Since 5-x²=(5-x)½ we have 5-x²>=0 ie -(5)½
i was able to think by substituting y assuming y = sq.rt of 5-x.
Thinking to relate it as parabola and Quadratic graph the only essence that the graph rotated.
So able to guess x=y.
7:30 made two perfect squares which came out to be of form a^2-b^2 than factorized it to two 2nd degree equations and hence got the 4 values of x
it was a really nice ques was able to do it with 2 diff methods and got to learn about third one which you told about 8:00
Thankkss
Here’s a way to solve the initial equation obtained of 4th degree:
X^4 - 10X^2 + X + 20 = 0
Factorising the 4th degree expression into two quadratics:
Let,
X^4 - 10X^2 + X + 20 = (X^2 + AX + B)*(X^2 + CX + D)
Comparing coefficients of X^3 in LHS and RHS,
C+ A = 0 or C = -A
Comparing coefficients of X^2 ,
D+ AC + B = -10 and because C = -A, hence
D- A^2+ B = -10 -(1)
Comparing coefficients of X,
AD + BC = 1 and because C = -A,
AD - AB = 1 or
A(D-B)=1 -(2)
Lastly comparing constant terms,
BD= 20 - (3)
Trying for integral solutions to (3), we obtain
B = -4 and D = -5 (by checking divisors of 20)
Putting B = -4 and D = -5 in (2),
We get A = -1
Now it remains to check if these values satisfy (1)
LHS = D- A^2+ B
= [-5] - [1] + [-4]
= -10
= RHS.
Therefore,
A = -1
B = -4
D = -5
And C = -A = 1
Hence, the original 4th degree expression can be factorised as
X^4 - 10X^2 + X + 20 =
(X^2 - X - 4)(X^2 + X - 5)
Now to find the roots,
(X^2 - X - 4)(X^2 + X - 5) = 0
The roots obtained are [1 (+-) sqrt(17)]/ 2
and [-1 (+-) sqrt(21)]/ 2
As the domain of the function can be found to be [-sqrt(5), +sqrt(5)]
The acceptable values of roots are 1/2*[1-sqrt(17)] and 1/2*[-1 + sqrt (21)]
QED.
This is not a general method, but often works for depressed quartics.
oo bhai 😦
X= (-1±√21) /2, given expression equates a function with its inverse, and we know that a function and it's inverse always meet at line y=x, therefore we can equate 5-x^2 with x to obtain the ans, but we have to check that whether they satisfy the condition and on checking we will obtain our final ans as X=(-1+√21) /2
okay, i loved it, i watch a lot of bprp and mind your decisions, post more such ques, loving these
8:50 me (2x²-1)² kyu hai (2x²+1)² hoga na due to b ka value
Yeh you're right
Are Ho jati h galti....
kay gajab solution h guru dev
2:26
if x^2 = t then x = +- root t
btw thanks for the question
eliminate kiye
using 1st equation
5-x^2>=0
7:28,understood,we need to take 5 as a variable and assume it as a quadratic
Thanks bhaiya for taking my suggested question. Ye question Maine ek bade achhe channel se liya tha, jiska naam hai "BlackPenRedPen". Us channel pe high school maths se high level maths ke achhe question mil jaate hain. Ye mujhe vahine se mila tha. I'll recommend everyone to checkout that channel also👍
another method we can do is creating prefect squares ....shift root(5-x) to the right add and subtract x we will see formation of 2 perfect squares {root(5-x)^2 - 1/2}^2 = (x- 1/2)^2 ...now we can easily solve these equations as it will reduce into 2 quadratic equations..😁
Good thought
Can someone tell me how did we eliminate the positive and negative roots at the last ?
5 ko variable ki tarah treat kiya aur x aur uske saare terms ko contsants bana diya. Aur uske solutions use karke x ki values bata di. x = (-1±√(21))/2 or x=(1±√(17))/2
Bhaiya yeh toh bohot easy sawal hai ... Trignometry use karke. Take √x=√5costheta maan ke baki toh manipulation hai x nikal jayega ..
We can also convert this to infinite nested root and we can solve that easily
thats what he did
Its almost wondeful to see people solve such beautiful equations, i saw this same equation 5 years ago on a channel black pen red pen. (Dear tejas i solved it or something like that was the title). Amazing to see this questions again after so long.
5 mai jab quad banaya ,,,tab toh dikh gya ,,, but pehle dikh pana was damn tough ,,,but koi nhi ,, now i know a new approach
I subtract -x both side and take (5-x )as a variable and then solve it and then it become just like a normal linear inequality
2 solutions will be missing..
That's whyy brooo
Be aware !!
Bolte hue bura to lag rha hai bavjood ki me khood bohot achha feel karunga agar koi meri baat samjega ... i know it is difficult to provide such amazing content free on yt but in previous time bhai aapne vo chiz provide karai thi .. aap apne set of 60 ke behtarine sawal late the yaha pe .. magar ab nahi late .. jo bhi reason ho magar aap wo content nahi to us level ka content plz provide karate rahie ....ha ese method kaam ke hai magar pura paper method wale ese qn ka to sirf calculation me use karenge na ki qn ki thought process me jo aap purane qn me build karvate the 😢😊😊
X=(1+√17)/2 lene pe original equation me put krne pe RHS -ve arha h jo ki nhi hoskta because under root of positive known quantity is always positive so aise ek case eliminate horha h , baki 2nd nhi click kra
This question can become more easy tell me my method is right or wrong according to the method √ 5 - x is equal to 5 minus x square root 5 is equal to 5 minus x square + x here 5 minus x square + X is and quadratic equation find the value of x using the quadratic formula we got the answer that x is equal to minus 1 + root 21 upon 2 which is the answer
For elimination any value thats between negative root 5 to positive root 5
Hi bhaiya I am also a jee aspirant aur maine aapka channel shorts pe bahut dekha h aur thank you for giving itne sahi question kuch kuch toh easy lgte h but kuch mein aisi band bajti h but thank you
Also main ek request kr rha hu ki please agr ho ske toh aap vaapis vo problem solving ki videos of every chapter lao na 😊 vo bahut acchi series thi please agr ho ske toh please laiye
Simply range nikal sakte hai equation ki which is negative root five to positive root five
Yes 7:10
5 mei quadratic man kar x ki value nikal na😊
2:35 if x²=t then x=±√t
People laugh at me whenever I have tried some similar approaches like this😢😢
They think I'm just crazy.
anyone who has watched the video how real men solve equations knew this approach
and it was discussed by blackpenredpen as well
maine ye socha ki pehle squaring karle and then quadratic jo ban rhi usko solve alag kare and =x^4 kar de then x^4 ko x^2x^2 karke jo factors bne the qudaratic ke usse equate akre to same a jayega at 9:24
5 is posive number
Bhaiya, y=√5-x and y=5-x² inverse functions hai.Then y=x pe unka root lie karega.
only for x>0. Ek solution aajayega, doosra nahi.
AS bprp said, believe in the power of geometry, considering making a triangle with said thingy
7:23 '5' me quadratic form ho gyi, toh quadratic formula lgayenge 5 ki value nikalne ke liye
For this can’t we take sqrt 5-x as the inverse function of 5-x^2 and make the eqn be equal at line y=x
7:23 par quadratic 5 ke terms mein bana lo
Bahut time lag Gaya karib 8-10😢😢😢min
Y=under root 5-x leke 5 ki value nikalke substitute Kar sakte hain original eqn mai cus usne fir x-y will cancel out after factoring
I just let x=5-y and put it in original equation then we get a quadratic in y and after solving we get x
7:27 solve by dharacharya and 5 as a root
fx=f'x give seen easily
it implies that
both of them equal to x
find x easily by quadratic formula
It is in Allen module function 12 question about no. Of sol
this function is f of x equal to f of y so symmetric about y=x
(1 - √17)/2 and (√21 - 1)/2
Bro when pointed out that it’s quadratic of five then it ringed very well thought loved it may be I can get types of question related to this that will be fun . Anyhow I enjoyed the solution very much it’s not everyday u get some nice ideas when solving
Glad to know bro 😁
Jo keh rhe h unse 1 baar me solve ho gya khud se
Meanwhile their jee main %ile
Pw ashish sir ne same approach se ek question class me karwaya tha jisme constant ko variable aur variable ko contant mana tha
5-x^2 has to be positive so roots (1+rt17)/2 and (-1-rt21)/2 are rejected
Not 1+rt17/2, I guess 1-rt17/2?
@@yuraje4k348 1-rt17/2 is a root and 5-x^2 is positive for it
@@armansrivastava665 oh yeah nvm
why would u eliminate 1+rt17/2, its positive
@@abhirupkundu2778 positive hone se koi farak nhi padta
Ek doubt hai bhai aapne jo yha per 3:16 x ko liya aise to hum Ramanujan submition ka solution laate hai but wo wrong approach bataya jata hai to yha sahi kaise ho jata hai
Ferrari method se hogaya use mostly 4 degree ho jati hai solve
Bhaiya ! I did thus que by geetting two parabolas and plotting them under the domain -✓5 to ✓5 (i saw one more guy with thus approach but he may get more roots is not considering the x domain)
x°2-y^2=x-y so[ x-y =0] or [x+y=1]
Thanks
Parabola hai circle hai paramteric coardinate se kr skte hai
No no no no
Ya ya ya
7:13 ab toh predict kar hi lenge 🤷, thumbnail me itna bada bada likha jo hai
8:55 choti si sign mistake bas
Bhaiya not gonna lie , at 7:08 when you wrote that equation , it stiked me to complete the square and everything followed up , btw amazing one ❤
Bhaiya graph se 2 solutions hai sahi hai kya 2 solution
Quadratic in 5 banti lag rahi hai.Title helped me