Question

Solve the system using substitution and show work.
-x-y-z=-8
-4x+4y+5z=7
2x+2z=4

Answer 1

@robtobey

Answer 2

Multiply both side of the first equation by 2 and then add the result to the third equation.
The x and z terms should subtract out leaving
-2 y = -12 or y = 6.

Can you proceed from here?

Answer 3

I'm a little confused on what I would do next, but I think if you explain what the next step is I'll be able to figure it out

Answer 4

I just tried to solve it an I'm really confused now. Can you write out the next step or next couple steps because I have no idea what I'm doing. My teacher didn't teach us the substitution method for these. He only taught us Cramers method.

Answer 5

The first two equations with every y replaced by 6:
{-6 - x - z = -8, 24 - 4 x + 5 z = 7}

Multiply the first one by -4 and then add the result to the second equation in order to
get rid of the x terms.

Your can then solve for z.

The answers are {x = 3, y = 6, z = -1}

Answer 6

Okay, that makes since now. Thank you!

Answer 7

Sorry it took so long. Had to reboot openstudy.com.
Been having problems lately and I don't think it lies with my Mac OS.

Answer 8

It's fine. I'm just glad I understand it now.

Answer 9

And thank you for the medal.