# How do you expand (3x + 1) ( 5x + 7)?

Jan 30, 2017

#### Answer:

See the entire solution 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.

$\left(\textcolor{red}{3 x} + \textcolor{red}{1}\right) \left(\textcolor{b l u e}{5 x} + \textcolor{b l u e}{7}\right)$ becomes:

$\left(\textcolor{red}{3 x} \times \textcolor{b l u e}{5 x}\right) + \left(\textcolor{red}{3 x} \times \textcolor{b l u e}{7}\right) + \left(\textcolor{red}{1} \times \textcolor{b l u e}{5 x}\right) + \left(\textcolor{red}{1} \times \textcolor{b l u e}{7}\right)$

$15 {x}^{2} + 21 x + 5 x + 7$

We can now combine like terms:

$15 {x}^{2} + \left(21 + 5\right) x + 7$

$15 {x}^{2} + 26 x + 7$