Question

Solve the system of equations by substitution. What is the solution for x?

2x + y = 1
4x + 2y = −2

Answer 1

My suggest would be to try and use the first equation to solve for y, in terms of x.
Then using that solution, replace y in the second equation and solve for x!

Answer 2

To use substitution you just solve one equation in terms of either x or y...then plug that equation into the other original equation and solve for the missing variable.

Original equations:
2x + y = 1
4x + 2y = −2

Let's go with the first equation and solve for y:
2x + y = 1 (original equation)
Therefore y=1-2x

Plug that equation into the the other (second original) equation:
4x + 2y = -2 (original equation)
4x + 2(1-2x)=-2
4x+2-4x=-2

Simplify to get:
2 = -2

Since that statement is wrong, there is no unique solution for the given equations.