Linear equations with unknown coefficients | Mathematics I | High School Math | Khan Academy

Sal solves the equations ax+3x=bx+5 and a(5-x)=bx-8 for x. Note that these equations include other unknowns (a and b) but we solve them for x.

High School Math on Khan Academy: Did you realize that the word "algebra" comes from Arabic (just like "algorithm" and "al jazeera" and "Aladdin")? And what is so great about algebra anyway? This tutorial doesn't explore algebra so much as it introduces the history and ideas that underpin it.

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[newfrontierfilms]

This didn’t help me. I’m still getting the questions wrong.

[samleheny]

I'm sure this will come in handy later, but this doesn't seem to get us very far. We're still left with a pretty mysterious expression as our answer.

[danialkhir]

Mr Khan you have been a great teacher to me during the time when it seems that everybody given up on me you have sparked my interest in learning and all I can say to you is thank you for being a great good man you are

[scorpio]

I'm retired and I can't begin to tell you how much I have benefited from relearning math using the Khan Academy. Sal is an outstanding instructor. Thank you so much! My one - and ONLY ONE - complaint is Sal's obsession with colors in his videos. I find the constant switching a waste of time and very distracting! But that is my only complaint. I love the math courses! THANK YOU!

[magdagurgenadze]

I was trying to solve the equation like this for 3 weeks, I just forgot school Algebra and can you imagine, how this video would be helpful for me? Thank you 1000 times! <3

[BJ]

Aren't you able to simplify even further by canceling out "a" in the numerator and denominator, add 8 + 5 to end up with x = 13/b?

[michaelaphillips]

Anyone else wondering where he pulled the negative one from???

[jessicamcbride]

To take this a step further, could we then cancel out the a in the denominator, which would leave "4a +8/b" ?

[minecraftezbuilds]

I know this but how do you find a and b

[salvadoro.]

In the 2nd problem would the answer be incorrect if you did not multiply the entire equation by -1???

[Greyhaven]

Why did he multiple both sides by -1 during the second example? How did he figure to do that? (Relearning everything I've forgotten/haven't learned) l. Just confused by this step and where it came from

[eengland]

Thank you, you literally just saved my algebra grade 👏🏻

[breannamarie]

in the second example, why did you multiply everything by -1? ( 4:05 )

[boarderq]

In the application I am trying to do the problems but the keyboard that comes up only has one symbol so I can not write the correct answer. How can I get a keyboard in the application with all symbols used in question.

[matthewseanpascual]

Why did he divide the 2nd problem by negative 1 before factoring out the x?

[SepaloidTV]

200k views and 71 likes, lmfao people hate this video... most likes probably teachers anyways