Question

Solve the system using an equivalent system.
-2x-y=0
3x-y=10

Answer 1

Not sure what it means by an equivalent system...?

But i'm guessing it means use eliminination

If you multiply the first equation by -1 (multiply EVERYTHING by -1) then you can add the first and second equations together,

Answer 2

solve for either x or y : -2x-y=0
Plug that answer into the 2nd equation.
Then plug in both those answers into the equations to check

solve for y:
-2x-y=0
-y=2x
y=-2x

Substitute:
3x-y=10
3x-(-2x)=10
5x=10
x=2

Now check
-2x-y=0
-2(2)-(-2(2))=0
-4+4=0

3x-y=10
3(2)-(-2(2))=10
6+4=10
10=10

Answer 3

An equivalent system means that both of the equations have the same answers

Answer 4

^ i don't think that's what it means: http://mrpilarski.wordpress.com/2009/12/06/3-2-solving-systems-of-equations-with-equivalent-systems/

like i thought, it means use elimination (not substitution)