How to check your answer to a system of equations, using substitution
Another example:
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
\[\begin{align*}
y &= 2x + 1 \\
-3 &=-2(2) + 1 \\
-3 &= -4 + 1 \\
-3 &= -3 \end{align*}\]
and
\[\begin{align*}
y &= x – 5 \\
-3 &=2 – 5 \\
-3 &= -3 \end{align*}\]
