Solving a Quadratic Equation by Factoring: Difference of Squares

Example: Solve the quadratic equation by factoring.

Original Equation
x^2-9=0
The equation already has all of the terms on the same side and zero on the other side. x^2-9=0
Factor the expression on one side.  The expression for this equation is a difference of squares. x^2-9=0
(x+3)(x-3)=0
Use the zero product property and set each factor equal to zero. (x+3)(x-3)=0
x+3=0 or x-3=0
Solve each equation. x+3=0 or x-3=0
x+3-3=0-3 or x-3+3=0+3
x=-3 or x=3