4 methods of solving quadratic equations, by factoring, taking sqrt, CTS, and quadratic formula

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  • Опубликовано: 18 дек 2024

Комментарии • 130

  • @krazieecko
    @krazieecko 6 лет назад +107

    @blackpenredpen it's been a year but the views have reached 10k are we getting the song?

  • @blackpenredpen
    @blackpenredpen  8 лет назад +39

    4 ways to solve quadratic equations

    • @lord_starscream.-i6y
      @lord_starscream.-i6y 8 лет назад +3

      blackpenredpen 只能說配方法萬能了

    • @blackpenredpen
      @blackpenredpen  8 лет назад +1

      Azir The Emperor of the Sands 是的!

    • @iustintaga
      @iustintaga 6 лет назад +1

      Pdf dont work

    • @t4g3d
      @t4g3d 6 лет назад

      When will you sing the quadratic formula song? Look at the view count 現在(12/6/2018)觀看次數:13,955
      啦! 曹老師請你快唱《二次方程之歌》吧!

    • @cursebr2937
      @cursebr2937 5 лет назад

      I have the fifth way k

  • @MichaelSmith-nc9iy
    @MichaelSmith-nc9iy 6 лет назад +36

    That tik tak toe factoring method was awesome. I've never seen that before, but it is a much neater way than the AC method I've been using. I love this channel, always learning something new. And even if it is something I already know, I seem to discover new insights and nuances to those concepts. Nice work man. Keep these awesome videos coming! Clearly though, I need to get a life, I'm having way too much fun watching math videos on a Friday night. I'm such a nerd.

    • @laurenlofton9039
      @laurenlofton9039 5 лет назад +1

      I’m more of a Slide and Divide person, but Tic-Tac-Toe does look more fun.

  • @chessandmathguy
    @chessandmathguy 7 лет назад +17

    in my view there are only 3 ways:
    1) factoring (if the problem allows for it)
    2) quad formula
    3) completing the square and then square rooting both sides.
    the method of just square rooting both sides only works if they already give you something with a complete square. in other words, it is the wrapping up of method 3. it's kind of like if they give you something that's already factored. just use the zero product property, but that's wrapping up method 1.
    from the form ax^2+bx+c=0, there is no way to just take square roots. you need to use one of the 3 methods above.

  • @LittleRapGuy
    @LittleRapGuy 3 года назад +1

    Great video... Did you sing the quadratic formula song? :0

  • @vishalmishra3046
    @vishalmishra3046 4 года назад +15

    (Best) Method 5: (derivative)^2 = discriminant. So, ax^2 + bx + c = 0 becomes (2ax+b)^2 = b^2-4ac. Rest is easy to solve by taking square root on both sides. The origin of this method is from ancient Indian Vedic mathematics (the original formula was in Sanskrit - चलित कलित वर्गो विवेचकः )

    • @geryz7549
      @geryz7549 2 года назад +2

      isn't this basically just the quadratic formula, if you square root both sides, then do -b and divide by 2a?

    • @dnuma5852
      @dnuma5852 2 года назад

      @@geryz7549 yeah i agree this is just quadratic formula but with more steps

  • @bim9429
    @bim9429 8 лет назад +14

    seriously, thank you for making these videos!! all of them help me a lot, and you explain it all in-depth and perfectly. I'm sure many other people including me appreciated your daily uploads~ keep it up!

    • @blackpenredpen
      @blackpenredpen  8 лет назад +3

      ashleigh 2.0 thank you for your nice words and I will

  • @xaviersson7047
    @xaviersson7047 8 лет назад +72

    i already knew the quadratic formula. but lets just make him sing!

  • @waterproof4403
    @waterproof4403 6 лет назад +5

    I hope this helps me with my GED
    I take it in 2 days!
    thanks for the video

  • @john99218
    @john99218 8 лет назад +2

    I've never heard the Quadratic Equation Song. I'm anxious to hear it now.... even if I have to review algebra to get it.

  • @3Lijahh
    @3Lijahh 11 месяцев назад

    Well done. Very well done 👏🏿👏🏿👏🏿

  • @makhosonkefab9566
    @makhosonkefab9566 3 года назад +1

    Good role model for us

  • @ralfbodemann1542
    @ralfbodemann1542 6 лет назад +16

    A good teacher has to keep his promise. When do we hear you sing the quadratic formula song?

  • @nullplan01
    @nullplan01 7 лет назад +2

    I always use the normal form formula, i.e. bring the equation into the form x²+ p x + q = 0. Then the result is x = - p/2 +- sqrt(p²/4 - q).
    If the equation is already of the form ax² + bx + c = 0, then just divide it all by a to get the normal form.

    • @wyattstevens8574
      @wyattstevens8574 2 года назад

      "M plus or minus square root of m squared minus p." (3blue1brown/Acapella Science) M = -b/2, P = [not to be confused with your linear variable] c, because b is the negative sum of the roots and c is their product.

  • @DaanSnqn
    @DaanSnqn 7 лет назад +1

    Almost 8000 views. You need to promote this video

  • @XaceLeem
    @XaceLeem 6 лет назад +2

    THANK YOU SO MUCH OUR TEACHER DOESNT EVEN TEACH AND THIS TAUGHT ME SO MUCH

  • @sofiatreccani1576
    @sofiatreccani1576 3 года назад

    excuse me but couldn’t we use the formula of the special trinomial at point 1:46?

  • @benjaminknudson5997
    @benjaminknudson5997 2 года назад

    what an awesome dude, I started using a black pen and red pen(and pencil) and I always think of him :)

  • @AlishiaWebster
    @AlishiaWebster 5 лет назад +2

    Break it down my bother!!!! Great job..

  • @alic3513
    @alic3513 2 года назад +1

    Thank yoooooouuuuuuuuuuuuu! you are the best sz

  • @rapidpep2611
    @rapidpep2611 4 года назад +3

    You seem so nice! Thank you so much for this video :3

  • @mmebled31sansnom26
    @mmebled31sansnom26 2 года назад

    Excellent leasson teacher
    Just exemple ( 3x - 1 ) (2× - 1 )= 0
    Thank you teacher
    See you

  • @holyshit922
    @holyshit922 7 лет назад +1

    I know another way to solve quadratic
    It works also for cubics and quartics
    First lets create system of equation
    x_{1}-x_{2}=d
    x_{1}+x_{2}=-a_{1}
    Last equation is sum of the roots and from Vieta we know that it is equal -\frac{a_{1}}{a_{2}}
    and I assumed that a_{2}=1
    Discriminant is symmetric function of the roots and we can transform first equation to be a discriminant
    x_{1}-x_{2}=d
    x_{1}+x_{2}=-a_{1}
    (x_{1}-x_{2})^2=d^2
    x_{1}+x_{2}=-a_{1}
    (x_{1}+x_{2})^2-4x_{1}x_{2}=d^2
    x_{1}+x_{2}=-a_{1}
    a_{1}^2-4a_{0}=d^2
    x_{1}+x_{2}=-a_{1}
    2x_{1}=-a_{1}+d
    2x_{2}=-a_{1}-d
    For cubics and quartics you have to create resolvent equation instead of using discriminant

  • @joelradasa3360
    @joelradasa3360 6 лет назад

    Very well-explained

  • @ZedTV8123
    @ZedTV8123 5 лет назад +1

    PDF link not working,..

  • @moezabid2969
    @moezabid2969 3 года назад

    I have another method for the first one :
    (3x-5)*(x+2)=4*5
    (3x-10)*(x+2)=(3*3-5)*(3+2)
    then x=3 is a first solution by identification and according to the polynomial formula : a(x-3)(x-b)=0
    thus a=3 and b*a*(-3) should equal (-30) because -30 is our constant in this equation
    so 3(x-3)(x+10\3)=0 and ×=-10\3 is a 2nd sol.

  • @jackrabbit2992
    @jackrabbit2992 5 лет назад +1

    The Link to the pdf is not up anymore

  • @lior1721
    @lior1721 6 лет назад

    Well you can solve this with differential calculus, give limits to the square (with the help of the deveriate) and use newton's method

  • @holyshit922
    @holyshit922 5 лет назад +1

    Completing the square method can be also used to reduce quartic equation to cubic equation

  • @s.bgamer823
    @s.bgamer823 4 года назад +1

    Love it from india

  • @kr-sd3ni
    @kr-sd3ni 4 года назад +3

    i always just use the quad formula whenever i see quad equations :D

  • @shermaine2372
    @shermaine2372 6 лет назад +2

    Thanks for this wonderful video!;)

  • @thatdude_93
    @thatdude_93 7 лет назад +1

    The Quadtratic Formula is so important in german maths education, that it's called the "Mitternachtsformel" which means "midnight formula". It's called that, because if someone wakes you up in the middle of the night and asks you what the formula is, you sould know it by heart.

    • @j0j083
      @j0j083 7 лет назад

      In der Schule habe ich nie davon gehört, stattdessen haben wir die p-q-Formel benutzt.

    • @Л.С.Мото
      @Л.С.Мото 5 лет назад

      @@j0j083 p q Formel ist ja auch ein Müll, welchen man nur im deutschen Müllsystem lernt.

  • @Magic73805
    @Magic73805 7 лет назад

    Really you are great.

  • @subversively6680
    @subversively6680 4 года назад

    Where is the pdf file, "page not found" error displayed???

  • @davidseed2939
    @davidseed2939 6 лет назад

    Here is a fifth way, guessing.
    The RHS is 20 which factors to 5*4
    By inspection x=3 gives (9-5)*(3+2) =20
    Can’t find the second root by inspection, so find the stationary point by differentiation Of the x x^2 terms
    Which is the average of the roots
    (3X^x +x)' = 6x+1 =0 , Xm=-1/6. =(xr +3)/2
    xr =-10/3

  • @ghazishaaban5253
    @ghazishaaban5253 6 лет назад

    you are so good

  • @dr.rahulgupta7573
    @dr.rahulgupta7573 3 года назад +1

    Fifth way : put ( d( ax^2+bx+c)/dx )^2= b^(2) --4ac this gives x1 , x2 directly . Wow !! Dr . Rahul

  • @IvyANguyen
    @IvyANguyen 8 лет назад

    Is it too advanced to explain the benefits of being able to solve by complete the square? I wish I knew earlier how much it would help when it comes to graphing polynomials. This can even help in calculus with curve sketching sometimes because you need not always take the derivative then find its zeroes, etc if you already can get the graph of the polynomial by doing some function transformations that can be found by completing the square. A polynomial in '(x + p)^2 + c' form is great for graphing for the p & c tell you how much of a shift you need to do to the x^2 polynomial to get the one you want to graph. No derivative & zeroes needed.

  • @newtonnewtonnewton1587
    @newtonnewtonnewton1587 5 лет назад

    We can solve it also by graphing to find the two points of x- intercipt

  • @Viesto1980
    @Viesto1980 6 лет назад +1

    pdf not found :(

  • @madscientist1595
    @madscientist1595 3 года назад

    I love the Quadratic formula superiority.
    But it was bit harder to do everything mentally.

  • @ninoadriandelrosario4356
    @ninoadriandelrosario4356 4 года назад

    Pls can you tell me what are the solution of 9t²-6t-8=0 im confused pls tell me the answer and the solution

    • @kiwithemaniaguy
      @kiwithemaniaguy 2 года назад

      Remember the quadratic formula :
      ax² + bx + c = 0
      x = -b ± sqrt(b² - 4ac) / 2a
      9t² - 6t - 8 = 0 :
      Know that : a = 9,b = -6,c = -8
      t = -(-6) ± sqrt((-6)² - 4 (9) (-8)) / 2(9)
      => t = 6 ± sqrt(36 - (-288)) / 18
      => t = 6 ± sqrt(324) / 18
      => t = 6 ± 18 / 18
      Therefore,we have other 2 same sol.
      t = -⅔ or t = 4/3

  • @tayseermagdy7805
    @tayseermagdy7805 4 года назад

    I can't find the pdf ?!

  • @mattheworchard481
    @mattheworchard481 3 года назад +1

    I don't really get the right side of the equation to equal 0.
    I do: x ² + cx = k → x = (± √ ( 4k + c ² ) - c )/ 2

  • @theophonchana5025
    @theophonchana5025 3 года назад

    (3x - 5) (x + 2) = 20
    3x^(2) + x - 10 = 20
    3x^(2) + x - 30 = 0
    (3x + 10) (x - 3) = 0

  • @theophonchana5025
    @theophonchana5025 3 года назад

    #trinomial #binomial #polynomial

  • @kenvng
    @kenvng 5 лет назад

    Thanks. Your links are not working any more... are you still doing this? can you send me a working link? Thank you

  • @salamander9763
    @salamander9763 6 лет назад

    what does the i mean in the square roots?

  • @Schlaousilein67
    @Schlaousilein67 2 года назад

    Nice

  • @vanesacoronado9791
    @vanesacoronado9791 6 лет назад

    Wow, amazing! Made my life so much easier! I'm in love thank you so much! :D

  • @theophonchana5025
    @theophonchana5025 3 года назад

    b^(2) - 4ac = 24

  • @Eashaans
    @Eashaans 8 лет назад +2

    10000 here we come!!

  • @risheraghavendira6042
    @risheraghavendira6042 4 года назад

    @blackpenredpen......as of Dec 26, 2020 there are 64000 views....but no song.....what a bummer!!😑😑😒😒

  • @DaanSnqn
    @DaanSnqn 6 лет назад

    Bprp you have 10000 views on this video

  • @bingodeagle
    @bingodeagle 8 лет назад +12

    lol imma share this with my math teacher and get you those 10000 views

  • @ajiwibowo8736
    @ajiwibowo8736 6 лет назад +1

    I use completing the square in 4th ways and i get x= 1/5 ± √5/5

  • @OonHan
    @OonHan 7 лет назад

    halfway there before your song

  • @harsh35842
    @harsh35842 4 года назад

    I also know an another method💐🙏

  • @theophonchana5025
    @theophonchana5025 3 года назад

    a = 5
    b = -2
    c = -1

  • @cursebr2937
    @cursebr2937 5 лет назад

    I have another way
    Using sum and product of roots

    • @wyattstevens8574
      @wyattstevens8574 Год назад

      I think I know what you mean: normalize by dividing by a, then write as x^2 - sx + p (s= sum, p= product) The solutions are (s = -2m ) m+/- sqrt (m^2 - p) which is exactly the same as the regular quadratic formula. (3Blue1Brown and Acapella Science described this method in a video on eigenvalues)

  • @mathphschjhb7749
    @mathphschjhb7749 7 лет назад

    PDF not found! 404 (Page Not Found) Error

  • @nicolas_heringer
    @nicolas_heringer 8 лет назад

    Just 10000 ? Think higher man !

    • @blackpenredpen
      @blackpenredpen  8 лет назад +1

      Nicolas Heringer that's just a small milestone. I do have videos with over 50000 views but I want to have this video being the first algebra video to be over 10000 views. : )

    • @nicolas_heringer
      @nicolas_heringer 8 лет назад

      I've already shared because brazilians loves people singing ! hahaha

    • @blackpenredpen
      @blackpenredpen  8 лет назад

      lol that's great! thanks

  • @w3nhan_
    @w3nhan_ 7 лет назад

    I'M SO DISTRACTED BY THE SUPREME SHIRT

  • @ChadTanker
    @ChadTanker 3 года назад

    this has now 70 k views and where is him singing the song?

  • @theophonchana5025
    @theophonchana5025 3 года назад

    #QuadraticEquation

  • @memecollector8648
    @memecollector8648 4 года назад +1

    Another method: shift solve

  • @anmolpandey9670
    @anmolpandey9670 5 лет назад

    He spells Ti as Thi
    Tic tac to as thic tha tho 😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😊😊😊

  • @kshitijgaur9635
    @kshitijgaur9635 6 лет назад

    Where can I send you my math doubts?
    Give your e-mail for that please

  • @srittampanigrahi4810
    @srittampanigrahi4810 4 года назад

    U can also solve By new method by Po-Shen-Loh discover in 25 Dec 2019

  • @andywright8803
    @andywright8803 7 лет назад

    Good video, but surely you shouldn't be studying complax numbers before you have quadratic equations totally sussed

  • @mihaiciorobitca3343
    @mihaiciorobitca3343 7 лет назад

    how old are you ?

  • @theophonchana5025
    @theophonchana5025 3 года назад

    x - 3 = 0
    x = 3

  • @natebaker2235
    @natebaker2235 6 лет назад

    almost to 10000 views

  • @tobiasvaldez5206
    @tobiasvaldez5206 5 лет назад

    Now is 5

  • @evohori
    @evohori 5 лет назад

    So basically I need to know at least two different methods(or should I learn all of them..I hate using too many methods for one thing)....one when factorable and one when factoring is not an option? I saw you did some stuff to rearrange the order of the equation....transfer the equal sign from left to right....what is that???! And you also reformed the first problem (looked like what you get after factoring a trinomial) into a normal looking quadratic equation!?!? I understand a quad equation can be factorable or not,but what is it with all the varying appearances?...it's annoying to me...3x^2+ -8- 12=0..........................(3x+5)(2x+5)..........3x^2=6x+9........how many variations are there and why

  • @theophonchana5025
    @theophonchana5025 3 года назад

    x + 2 = 20
    x = 18

  • @kingbaldwin0
    @kingbaldwin0 6 лет назад +1

    He wore supreme before it was cool.

  • @DaanSnqn
    @DaanSnqn 6 лет назад +2

    You got 10000 views. Now sing!

  • @mishikookropiridze
    @mishikookropiridze 7 лет назад +7

    I personally hate the quadratic formula , its very ugly and doesn’t prove student’s ability of solving problems

    • @Whadatd
      @Whadatd 5 лет назад +2

      Misho Okropiridze neither do the other 3 ways

  • @OonHan
    @OonHan 7 лет назад

    Nearly there
    if you wont sing, i will when i have at least 30 subs

  • @kentginbautistadandan5588
    @kentginbautistadandan5588 2 года назад

    you're cute ❤

  • @theophonchana5025
    @theophonchana5025 3 года назад

    #linearequation #factoring #factor