Question

How do you check your solutions to a systems of equations using the substitution method?

Answer 1

I created a video with a more detail explanation here.

To check a system of equations by substitution, you plug your values for x and y into the original equations. If both simplified expressions are true then your answer is correct.

For example: To check if `(2, -3)` was the correct solution for the system of equation: `y = -2x + 1` and `y = x - 5`,
substitute 2 for x and -3 for y into each equation

`y = -2x + 1`
`-3 = -2(2) + 1`
`-3 = -4 + 1`
`-3 = -3`

and

`y = x - 5`
`-3 = 2 - 5`
`-3 = -3`

Since `x = 2` and `y = -3` worked for both equations I know that `(2, -3)` is the solution to this system of equations.