Question

I am solving sytems of equations algrbraically. I have tried several times and I am not comming up with he answers for the following three equations that the book gives.

1) 4x-2y=-5
-x+2y=2

Answer in book: -1,1/2

2) -5x+2y=10
5x-3y=-10

Answer in book: -2,0

3) 2x-y=2
-2y+4y=-5

Answer in book: 1/2,-1

Answer 1

4x-2y=-5
-x+2y=2

Adding the two equations together gives

4x-2y+-x+2y=-5+2

the ys on the LHS cancel to give

4x-x=-3
3x=-3
x=-1

substitute x=-1 into one of the starting equations.

4(-1)-2y=-5
-4-2y=-5

-2y=-1
y=1/2

Have a go at the others.