Question

Consider the following pair of equations:

y = −2x + 8
y = x − 1

Explain how you will solve the pair of equations by substitution. Show all the steps and write the solution in (x, y) form.

Answer 1

(3,2)

Explanation:

y = -2x + 8

y = x-1

Substitute x-1 for y in the equation y = -2x + 8. x-1 = -2x + 8

Use the Additive Property to move the

constant terms to one side of the equation. x-1 = -2x + 8

+1 +1

x = -2x + 9

Now do the same to the variable terms. +2x +2x

3x = 9

Divide both sides of the equation by the

constant in the variable term. ÷3 = ÷3

x = 3

To find y, simply substitute the value of x into

one of the original equations. y = x-1

y = 3-1

Solve: y = 2

The solution is (3, 2).