Question

2x-4y=8 3x+8y=-2 solve using elimination

Answer 1

2x+5y=13 multiply both sides by 3
6x + 15y = 39

3x - 4y = 8 multiply both sides by -2
-6x + 8y = -16 add the two new equations to each other

(-6x + 8y) + (6x + 15y) = 39 + (-16)
-6x + 6x + 8y + 15y = 39 -16
0x + 23y = 23
23y = 23
y = 1

2x + 5y = 13 sub in 1 for y
2x + 5(1) = 13
2x + 5 = 13
2x = 8
x = 4

answer (4,1)

check:
3(4) - 4(1) = 8
12 - 4 = 8
8 = 8

Answer 2

2(2x-4y=8) = 4x-8y = 16
3x+8y=-2

4x-8y=16
3x+8y=-2
the 8s cancel out

4x+3x = 14
7x=14

x=2

2(2) - 4y = 8
4-4y = 8
-4 -4
-4y=4

y=-1


x=2
y=-1
(2,-1)