Question

Solve the system

-3x+4y=-6
5x-3y=-22
3y+2z=-1

I'm not sure how to approach this question because all of the equations are missing a variable??

Answer 1

actually it is good when variables are missing, it makes it easier.

your first two are just in x and y, so solve these two.

first one times 3 ---> -9x + 12y = -18
2nd one times 4 ---> 20x - 12y = -88
add them
11x = -106
x = -106/11
then -3(-106/11) + 4y = -6
y = -96/11

in the third:
3(-96/11) + 2z = -1
z = 277/22

crazy answers, but they work.
Are you sure you typed them correctly?

Answer 2

OMG, sorry reiny, i didn't think anyone was going to help me out on this one so i reposted it (again with the wrong equation)... the correct one is..
-3x=4y=-6
5x-3z=-22 (3z instead of 3y)
3y+2z=-1

Answer 3

And now you made a typo in the first , lol

OK, I think you meant ....
-3x+4y=-6
5x-3z=-22
3y+2z=-1

2nd by 2 ---> 10x - 6z = -44
3rd by 3 ---> 9y + 6z = -3
add them: 10x + 9y = -47 (#4)

1st by 10 ---> -30x + 40y = -60
4th by 3 ----> 30x + 27y = -141

add them: 67y = -201
y = -3 , YEA!!

now backsubstitute.....

Answer 4

Thank you very much Reiny, and Goodnight :) no more questions for now :)