# How do you multiply (a-7)(a-3)?

Mar 3, 2017

See the entire solution process below:

#### Explanation:

To multiply these two terms together you multiply each of the terms within the left parenthesis by each of the terms in the right parenthesis:

$\left(\textcolor{red}{a} - \textcolor{red}{7}\right) \left(\textcolor{b l u e}{a} - \textcolor{b l u e}{3}\right)$ becomes:

$\left(\textcolor{red}{a} \times \textcolor{b l u e}{a}\right) - \left(\textcolor{red}{a} \times \textcolor{b l u e}{3}\right) - \left(\textcolor{red}{7} \times \textcolor{b l u e}{a}\right) + \left(\textcolor{red}{7} \times \textcolor{b l u e}{3}\right)$

${a}^{2} - 3 a - 7 a + 21$

Now, combine like terms:

${a}^{2} + \left(- 3 - 7\right) a + 21$

${a}^{2} - 10 a + 21$