Question

solve by the elimination method3x+4y=4
6x+8y=-8

Answer 1

Divide the second equation by 2 it will make your calculations easier

Answer 2

No solution to this system

Answer 3

You will want to multiply the top one by -2 (in order to get one of the terms to cancel out.
You end up with:
-6x-8y=-8
6x+8y=-8
Add the two to get
0 = -16
No solution

Answer 4

3x + 4y = 4
3x + 4y = -4
When you subtract equation (1) from equation (2) You have the same terms on left hand side so you get:
0 = 8...This is not true therefore your system has no solution