# How do you multiply (x - 7) (x + 7)?

Jul 13, 2015

=color(blue)(x^2-49

#### Explanation:

color(blue)((a-b)(a+b) = a^2-b^2

The same property can be applied to the expression $\left(x - 7\right) \left(x + 7\right)$ where $\textcolor{b l u e}{a} = x , \textcolor{b l u e}{b} = 7$

So,
$\left(x - 7\right) \left(x + 7\right) = {x}^{2} - {7}^{2}$

=color(blue)(x^2-49