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

1 Answer
Jan 26, 2015

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.