Question

Another elimination method equation. Please help, this is very frustrating.

8u + 3v = -15
3u + v = -6
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11u + v = -21

I add those up but now dont know where to go

Answer 1

Before you add them up, you have to make sure the variable you want to eliminate has the same coefficient on both equations but with different sign.
The v on the second equation has coefficient 1, the v on the first has coefficient 3, how would you get the second equation v to have -3?

Answer 2

multiply -4 to the second equation…. ok I see now

Answer 3

I mean -3***

Answer 4

Correct, then substitute the resulting equation for equation 2 and add to the first equation.

Answer 5

tell me how off I am, I got (3,-3) for everything

Answer 6

So u=-3 and v=3, right?

Answer 7

um actually the opposite u=3, v=-3 :/

Answer 8

Substitute them into the first equation. That wouldn't work.
8(3) + 3(-3) = -15
This comes out to 15=-15 which is wrong, so that wouldn't work.

Answer 9

Ahh I see what i did wrong. Ok ..

Answer 10

Ok, good luck.

Answer 11

Thanks so much for walking me through this.