# How do you factor by grouping 63n^3 + 54n^2 - 105n - 90?

May 10, 2018

$3 \left(7 n + 6\right) \left(3 {n}^{2} - 5\right)$

#### Explanation:

$\text{take out a "color(blue)"common factor } 3$

$= 3 \left(21 {n}^{3} + 18 {n}^{2} - 35 n - 30\right)$

$= 3 \left(\textcolor{red}{3 {n}^{2}} \left(7 n + 6\right) \textcolor{red}{- 5} \left(3 n + 6\right)\right)$

$= 3 \left(\left(7 n + 6\right) \left(\textcolor{red}{3 {n}^{2} - 5}\right)\right)$

$= 3 \left(7 n + 6\right) \left(3 {n}^{2} - 5\right)$