Question

I forgot how to do this multiply (a-4)(a+4)

Answer 1

FOIL

\((a-b)(c+d)=ac+ad-bc-bd\)

Answer 2

\[
(\color {blue}a\color{red}{-4})(\color{green}a+\color{orange}4)
=\color {blue}a\color{green}a+(\color{red}{-4})\color{green}a+\color{orange}4\color {blue}a+(\color{red}{-4})(\color{orange}4)
\]