# How do you find the product (6y-7)(6y+7)?

Apr 22, 2017

$36 {y}^{2} - 49$

#### Explanation:

Each term in the second bracket is multiplied by each term in the first bracket. This can be achieved as follows.

$\left(\textcolor{red}{6 y - 7}\right) \left(6 y + 7\right)$

$= \textcolor{red}{6 y} \left(6 y + 7\right) \textcolor{red}{- 7} \left(6 y + 7\right)$

$= \left(\textcolor{red}{6 y} \times 6 y\right) + \left(\textcolor{red}{6 y} \times 7\right) + \left(\textcolor{red}{- 7} \times 6 y\right) + \left(\textcolor{red}{- 7} \times 7\right)$

$= 36 {y}^{2} + 42 y - 42 y - 49$

$= 36 {y}^{2} - 49 \leftarrow \textcolor{m a \ge n t a}{\text{ difference of squares}}$