I'll be honest, I don't pay attention in class because I know I'll just come home and watch The Academy's video. The bonus factor is that I will understand in under 15 minutes what my teacher struggles to explain in 50 minutes.
I wish they'd go through equations that didn't work so well. ike equations where you have to do a little more and it doesn't all just seamlessly fit together
I want to cry, ive been studying this for hours and just couldnt get it (have a math test tomorrow). This video made me understand it all THANK YOU SO FUCKING MUCH
I get it on here but look at my homework and go what is this. My homework is out of the prentice hall algebra 2 book and you can learn one thing sitting in a class where the problems are simple but get the homework and it’s like I don’t understand it.
Thanks, this video was very helpful for me. Tomorrow I'll be taking my math exams and rational equations were one of them.. Thanks a lot Khan Academy!!!
Is the... method of transforming rational algebraic equatiion to quadratic equation present .?? Right Thanks .....a lot... i owe you ..my presentatio and assignment ia pres...
I've been struggling with this for so many hours, I have a quiz I need to asnwer due today and the way our teacher taught us in our online class, I didn't really understand. Thanks for the vid!!!
He just simplified both sides of the equation. He had: 5/35 = 2/14. 5 divided by 35 = 1/7. 2 divided by 14 = 1/7. Since 1/7=1/7, that means that the value of "x" which he put in is the correct one and is a solution.
My teacher does a horrible job explaining things, plus the fact that she just shows us what to do instead of how and why you do it, and on top of THAT it's hard for me to understand math quickly. This really helped. A 42 minute ill explained lesson compressed into a 13 minute well explained lesson
at 4:25 I dont understand how you take x^2 + 2x -8 and factor it down to x+4 times x-2. I see were x+4 is because the power of two but i cant figure out how you get the x-2
Here's the explanation even though it's super late hahaha He factored the denominator x^2+(2)x+[8] ____+____=(2) ____•____=[8] ^ ^ 4 -2 So the factored form of x^2+2x-8 is (x+4)(x-2)
Hi, I have a question I'm struggle with for hours now. Why do we not multiply the denominator by the Least Common Factor too if we're solving the equation? But if we're simplifying an expression, dont we have to multiply both nominator and denominator by the LCF too?
But he's not explaining the quadratic formula in this video, therefore, he would just get through it fast. The explanation for solving rational equation was pretty detailed though.
I learned that shit already in advance math but we never simplfied the square root... We left it as it was bc we werent allowed to use decimals unless it was a perfect square and 113 isnt a perfect square...
I don't know how fast you could respond to this question but in my college algebra 1 class I'm struggling to understand this equation with rational equations. It's x^2 - 10x + 25/ 3x-5
I know this comment will go unseen here, but I'd feel guilty if I didn't thank Khan Academy for the full lesson they just taught me in less than a quarter of what my teacher would spend on the same topic. Thank you!
I'm confused as to how you were able to rewrite x^2+2x-8 into x+4*x-2. I know it is possible, but I don't know how you did it. If someone could explain this, that would be great (: @4:26
Hey, I know am 3 years late but there may be others with the same question as you so here I'll simplify it step by step. Step 1: AC Method The quadratic x^2+2x-8 is in the form ax^2+bx+c. This will work for any trinomial. It's called the AC Method because we multiply A and C, which in this case is 1 (because the coefficient of x^2 is 1) and -8 and we get -8. Step 2: Factoring Now that we have the number -8, we have to find a pair of numbers that when multiplied will equal C (-8) and when added will equal B (2). You can go ahead and list the factors, like 1 and -8 is a pair, or -4 and 2. Once you get the hang of it, you can quickly factor in your head. He saw that 4 and -2 multiply to get -8 and add to get 2, which is why he ended up with turning that into (x+4)(x-2). Hope this helps :)
@@jah-4 Haha, well thanks anyways! I'm sure it helped others. 3 years later, I can look at the equation and figure it out now, so I guess I am testament to the success of the schooling system.
You can solve it in your head, but if you don't have a calculator you can leave the square root without solving it. You could also simplify the radical expression, unless its a perfect square root. Its weird that you're not allowed to use a calculator though
Haha he turned the equation into a quadratic formula. It’s how you can solve quadratics and you can do it when you have an equation where the first term has an x and is squared, and second term with an x (not squared) and a regular number. When there are usually three terms like that, you can plug in the values (not including the x’s) into the quadratic formula to solve the quadratic.
+Anonymous User Using the "quadratic formula" you can determin what X is equal to. So if you get a complicated question where your final quadratic cannot be used by factoring, you use the quadratic formula.
For the future people cramming their Algebra test (like me hehe) and scrolled down the comments section to ask where the hell the square root came from, it's because he used the quadratic formula to factor the equation. And you SHOULD know what the quadratic formula is, since you should've learned that from solving quadratic equations.
I'll be honest, I don't pay attention in class because I know I'll just come home and watch The Academy's video. The bonus factor is that I will understand in under 15 minutes what my teacher struggles to explain in 50 minutes.
So true
hahaha me 24/7
mine is different i pay attention to class and dont understand shit then come here but still 50/50 im at grade 11 by the way
I'm at Grade9 and damn it's so hard.
8th grader here. Can't understand a thing
I wish they'd go through equations that didn't work so well. ike equations where you have to do a little more and it doesn't all just seamlessly fit together
Exactly
I want to cry, ive been studying this for hours and just couldnt get it (have a math test tomorrow). This video made me understand it all THANK YOU SO FUCKING MUCH
You're welcome.
Please don't swear in this minecraft christian server
How are you now?
This 12 minute video has me understanding this unit more than my teacher trying to teach me for 55 minutes...
+Bobby V I know right. Me too.
Yeah same with me too. Wish all our teachers we're like this video, short and simple
Exactly
I dont comprehend well so i understand but my class period is 90 minutes so i would know you pain. Im not that good in Algebra 2
All this work would make you think you solve something super complex.
Nope. Just a line on a graph.
I hate my life.
Sometimes I wish that I have the same mind as the one speaking in terms of mathematics.
Sal, first of his name.
Love your headshot
Same.
Why is math so god damn difficult
retweet
Because you don't study?
It’s made to be confusing .....
@@diegocordero676 its the skill, you're just being dry
@@aiexzs simp
Remember when a math problem could be written in 5 seconds not 12 minutes??
I get it on here but look at my homework and go what is this. My homework is out of the prentice hall algebra 2 book and you can learn one thing sitting in a class where the problems are simple but get the homework and it’s like I don’t understand it.
i love how he types everything out even,
"let me scootch it over a little bit...."
Math is the devil's language.
Addie Seidel Don’t put that evil on him. 😂, he’s about having fun.
@@el290 😂 have you seen the tv show Lucifer yet?
Faaaaaaacts!
Khan plz never stop these videos, bc my teachers r terrible and I understand bc of u!!!
I learn more from watching khan academy then I do sitting through a 55 minute class
To true and my classes are 1hr and 30min... tells you that he should build education systems shouldnt he...
+Brian Hunter Oehme Me too.
But I don't have a good Algebra 1 teacher.
Thank you sooooo much, I'm taking the Precalc CLEP exam and this is soooo much help.
Teaches me more in the first 5 minutes than 90 minutes of teacher time. Amazing.
Bro just saved my life bc I have a final today and couldn't remember how to do this
Thanks, this video was very helpful for me. Tomorrow I'll be taking my math exams and rational equations were one of them.. Thanks a lot Khan Academy!!!
Is the... method of transforming rational algebraic equatiion to quadratic equation present .??
Right
Thanks .....a lot... i owe you ..my presentatio and assignment ia pres...
+lloyd ancajas ???
Never mind ....important is i am happy with this video
I think people learn more from khan academy is because he doesn't use the core learning system
you dont understand how much i love you, my teacher is probably 100 and can barley explain to me anything. you made things so clear to me, thank you.
I've been struggling with this for so many hours, I have a quiz I need to asnwer due today and the way our teacher taught us in our online class, I didn't really understand. Thanks for the vid!!!
He teaches better then my teacher.
He just simplified both sides of the equation. He had: 5/35 = 2/14. 5 divided by 35 = 1/7. 2 divided by 14 = 1/7. Since 1/7=1/7, that means that the value of "x" which he put in is the correct one and is a solution.
My teacher does a horrible job explaining things, plus the fact that she just shows us what to do instead of how and why you do it, and on top of THAT it's hard for me to understand math quickly. This really helped. A 42 minute ill explained lesson compressed into a 13 minute well explained lesson
Learn this stuff early on kids, because learning it at 37 is a fucking pain in the ass
at 4:25 I dont understand how you take x^2 + 2x -8 and factor it down to x+4 times x-2. I see were x+4 is because the power of two but i cant figure out how you get the x-2
Lol, same dude. I was confused in that part. I thought it was just me... thanks for existing in the comment section!;)
Here's the explanation even though it's super late hahaha
He factored the denominator
x^2+(2)x+[8]
____+____=(2)
____•____=[8]
^ ^
4 -2
So the factored form of x^2+2x-8 is
(x+4)(x-2)
i literally love you thank you sm for teaching me this
Hi, I have a question I'm struggle with for hours now. Why do we not multiply the denominator by the Least Common Factor too if we're solving the equation? But if we're simplifying an expression, dont we have to multiply both nominator and denominator by the LCF too?
you're awesome man, i love how you teach. thanks!
it would help if you explain every step in more detail when you get to end .
But he's not explaining the quadratic formula in this video, therefore, he would just get through it fast. The explanation for solving rational equation was pretty detailed though.
4:02, it supposed to be x to the power of two +2x+2! Not x to the power of two +2x-8! -2+4 is equals to positive 2!
Pretty good except ya kinda lost me when the whole quadratic equation stuff... The worst part is that we went over this stuff in math class
For the second problem how did you get x+4 and x-2 as your least common multiple?
same dude
I learned more in this video than the entire unit my teacher taught on this for 3 weeks
**initiate confused screaming**
thank you so much for helping the students like me
nah dawg this is much easier that i thought after you explained
4:41 Isnt x times -2 equal to -2x and not +2x?
ETIFETIS: Each Term In the First Times Each Term in the Second. So much better than the old school FOIL, because it doesn't work on trinomials.
Hey why on the first example you add 8?
BTW We're probihited to use Calculator T-T
Well when you want to remove the -8 from one side, you have to add 8. That makes it zero, and one thing you do on one side you do on the other.
You have to add 8 to both sides so they cancel out
"Hopefully you found that slightly instructive"? more like incredible instructive!
Wow...much better than my math teacher
I learned that shit already in advance math but we never simplfied the square root... We left it as it was bc we werent allowed to use decimals unless it was a perfect square and 113 isnt a perfect square...
You could simplify the sqrt of 113 though
under x^2+2x-8 how did you quickly get (x+4)(x-2) ..I just checked to see if it breaks down into that, but it was no hesitation for you.
I don't know how fast you could respond to this question but in my college algebra 1 class I'm struggling to understand this equation with rational equations. It's x^2 - 10x + 25/ 3x-5
i have a test tomorrow and i’ve been pulling an all nighter just to get one question right. came to this and got it in less than 10 minutes
7:40 ya lost me here
Quadratic formula, its when you want to find the zeros or roots of the equation. Its really easy once you get the hang of it
You failed
In wich video does he teach about adding numbers to both sides?
I know this comment will go unseen here, but I'd feel guilty if I didn't thank Khan Academy for the full lesson they just taught me in less than a quarter of what my teacher would spend on the same topic. Thank you!
I'm confused as to how you were able to rewrite x^2+2x-8 into x+4*x-2. I know it is possible, but I don't know how you did it. If someone could explain this, that would be great (: @4:26
Hey, I know am 3 years late but there may be others with the same question as you so here I'll simplify it step by step.
Step 1: AC Method
The quadratic x^2+2x-8 is in the form ax^2+bx+c. This will work for any trinomial. It's called the AC Method because we multiply A and C, which in this case is 1 (because the coefficient of x^2 is 1) and -8 and we get -8.
Step 2: Factoring
Now that we have the number -8, we have to find a pair of numbers that when multiplied will equal C (-8) and when added will equal B (2). You can go ahead and list the factors, like 1 and -8 is a pair, or -4 and 2. Once you get the hang of it, you can quickly factor in your head. He saw that 4 and -2 multiply to get -8 and add to get 2, which is why he ended up with turning that into (x+4)(x-2).
Hope this helps :)
@@jah-4 Haha, well thanks anyways! I'm sure it helped others. 3 years later, I can look at the equation and figure it out now, so I guess I am testament to the success of the schooling system.
4:31 Where did the 4 come from? Sure, it’s on the left side but how did you just pull it out of the right side?
What do we do if we are not allowed to use calculator
you lose
You can solve it in your head, but if you don't have a calculator you can leave the square root without solving it. You could also simplify the radical expression, unless its a perfect square root. Its weird that you're not allowed to use a calculator though
what the frack, where did the square root come from?
Haha he turned the equation into a quadratic formula. It’s how you can solve quadratics and you can do it when you have an equation where the first term has an x and is squared, and second term with an x (not squared) and a regular number. When there are usually three terms like that, you can plug in the values (not including the x’s) into the quadratic formula to solve the quadratic.
@@zango3134 I love that you replied to a 7 year old comment. What a legend, thank.
This video was a lifesaver!
God bless this atrocity that is math
I didn't understand what did you do at 2:27
same!
3:06 does anyone know what to do if you have something like negative X on one side but nothing on the other
you sir are a god
what is x minous y, over 4, plus x plus y, over 3 = 1 ,if you have to resolve for y
Thank you!! This helped me with my hw.
thanm you for this. its very helpful
I love being the first to watch a video :P Thank you fo rall the help and I love your videos!
How you doing mate hahaha
same lol cant belive i scroled all the way to the bottoms
Thanks, now i understood when you had to use a calculator.
Thanks sir
I lost you at 8:00
+Anonymous User Using the "quadratic formula" you can determin what X is equal to. So if you get a complicated question where your final quadratic cannot be used by factoring, you use the quadratic formula.
Its the quadratic formula, he just plugged in the a, b and c terms into the quadratic equation. x=-b+-sqrt(b^2-4ac)/2a
WAIT! pleassee! How did it became minus 5x (-5) for both sides? at 2:53 ??
Omg thank you so much i understand it better thx!!!
Khan Academy is my new best friend.
my teacher isn’t good…i literally spend hours teaching myself
I better hope I get better at math with this.
congrads you helped save my grade
Thanks it really helped me!
Thanks for the explanation
dude, you are a genius
why use negative 5 to cancel
The best 13 min ever
"Let's do a more involved problem."
I love you omg helped me so much 😭
Omg thank you for your guidance.
Wow we just started this stuff yesterday
Thank you.........
im a trying to learn grade 9 maths as a grade 7 for a entrance exma for my ney school on the equation at 2:53 why did he add the -5x
On 8:00 can't you also factor that?
you were doing swell until you got to the square root parts.....That is so Confusing!!!!!!!!!
that's just the quadratic formula. very easy problem comparing to what's on my upcoming 7th grade algebra honors test tomorrow.
Why did he add the 11 ? Shouldn’t it be 11 - 10.63 ?
PERFECT! thanks!
I always beg my students to determine the domain of rational functions first and without exception.
why dont you make questions in the description to ask students, and then in the next video put the answers
you do realize this video was made in 2010, right?
@@seadawn8559 nope
does anyone what he wrote? im lost because all the numbers
@cyclone2876 wtf no its not. he uses a usb drawing pad
Thank you!
bless khan academy
@zacrichards1
maybe this is photoshop (using a graphic tablet)
For the future people cramming their Algebra test (like me hehe) and scrolled down the comments section to ask where the hell the square root came from, it's because he used the quadratic formula to factor the equation. And you SHOULD know what the quadratic formula is, since you should've learned that from solving quadratic equations.
Lol same here
kahn you saved my life long learned
Just quadratic formula
I don’t understand. This feels exactly like my teachers explanation.
san nang galing yung 5x tol?
Why can't you just cross multiply?
This was more less of a video explaining the quadratic formula.