# How do you factor 6m^3+15m² - 2m - 5?

##### 1 Answer
Jul 31, 2016

$\left(2 m + 5\right) \left(3 {m}^{2} - 1\right)$

#### Explanation:

Group the terms into 'pairs' as shown.

$\left[6 {m}^{3} + 15 {m}^{2}\right] + \left[- 2 m - 5\right]$

now factorise each 'pair'

$\Rightarrow \textcolor{red}{3 {m}^{2}} \left(2 m + 5\right) \textcolor{red}{- 1} \left(2 m + 5\right)$

there is now a common factor of (2m + 5) which can be taken out.

$\left(2 m + 5\right) \textcolor{red}{\left(3 {m}^{2} - 1\right)}$

$\Rightarrow 6 {m}^{3} + 15 {m}^{2} - 2 m - 5 = \left(2 m + 5\right) \left(3 {m}^{2} - 1\right)$