We can apply the and compare the result with the given expression.
(x + 3) (x - 3)
x (x + 3) - 3 (x + 3)
x^2 + 3 x - 3(x + 3)
x^2 + 3 x - 3 x - 9
x^2 - 9
After applying the Distributive Property and simplifying, the result is the same as the given expression. Therefore, we can be sure our solution is correct!