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

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

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Answer 1 · 2015-01-26T15:28:24

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 $(2, - 3)$ $(2, -3)$ was the correct solution for the system of equation: $y = - 2 x + 1$ $y = -2x + 1$ and $y = x - 5$ $y = x - 5$ ,
substitute 2 for x and -3 for y into each equation

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

and

$y = x - 5$ $y = x - 5$
$- 3 = 2 - 5$ $-3 = 2 - 5$
$- 3 = - 3$ $-3 = -3$

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

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

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