How do you multiply (7+2a)(7-2a)?

Jan 18, 2017

See the entire multiplication process below:

Explanation:

To multiply these two terms you multiply each individual term in the left parenthesis by each individual term in the right parenthesis.

$\left(\textcolor{red}{7} + \textcolor{red}{2 a}\right) \left(\textcolor{b l u e}{7} - \textcolor{b l u e}{2 a}\right)$ becomes:

$\left(\textcolor{red}{7} \times \textcolor{b l u e}{7}\right) - \left(\textcolor{red}{7} \times \textcolor{b l u e}{2 a}\right) + \left(\textcolor{red}{2 a} \times \textcolor{b l u e}{7}\right) - \left(\textcolor{red}{2 a} \times \textcolor{b l u e}{2 a}\right)$

$49 - 14 a + 14 a - 4 {a}^{2}$

We can now combine like terms:

$49 + \left(- 14 + 14\right) a - 4 {a}^{2}$

$49 + 0 - 4 {a}^{2}$

$49 - 4 {a}^{2}$

$- 4 {a}^{2} + 49$