How do you solve 4x+y=-5 and 2x+3y=5 using substitution?

1 Answer
May 25, 2018

x=-2
y=3

Explanation:

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

Rearrange the first equation for y:

4x+y=-5

y=-5-4x

Substitute y into second equation and solve for x:

2x+3y=5

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

2x-15-12x=5

2x-12x=5+15

-10x=20

x=20/-10

x=-2

Then substitute the value of x into one of the original equations to find the solution for y:

4x+y=-5

4(-2)+y=-5

-8+y=-5

y=-5+8

y=3

Double check your solution by substituting values of x=-2 and y=3 into any of the original equations and see whether you get the numerical solution (-5 or 5).