We can apply the and compare the result with the given expression.
(a + 7) (a - 7)
a(a + 7) - 7 (a + 7)
a^2 + 7 a - 7(a + 7)
a^2 + 7 a - 7 a - 49
a^2 - 49
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!