Question

Solving systems of linear equations in 3 variables...

1) 3x-2y+2z=1
2) 2x+5y-5z=7
3) 4x-3y+z=-3

I combined 1 and 3 to get -5x+4y=7
And then i combined 2 and 3 to get
-13y+11z=-17. Can that be right? how would you combine those two equations?

Answer 1

you should when combining 2 and 3, multiply to get rid of z, so multiply 3 by 5, then add.

Answer 2

You would like to have the same two variables in the two new equations.
Your first one contains x and y, but your second contains y and z. This gets you nowhere.

Your first equation is ok,
Now take 5 times the third and add it to the second.

Answer 3

So you would get 22x-10y=-8? how would you combine that with -5x+4y=7?

Answer 4

THanks guys! i get it now!