# How do you factor x^3-4x^2-36x+144 by grouping?

Aug 7, 2016

${x}^{3} - 4 {x}^{2} - 36 x + 144 = \left(x + 6\right) \left(x - 6\right) \left(x - 4\right)$

#### Explanation:

${x}^{3} - 4 {x}^{2} - 36 x + 144$

= ${x}^{2} \left(x - 4\right) - 36 \left(x - 4\right)$

= $\left({x}^{2} - 36\right) \left(x - 4\right)$

= $\left({x}^{2} - 6 x + 6 x - 36\right) \left(x - 4\right)$

= $\left(x \left(x - 6\right) + 6 \left(x - 6\right)\right) \left(x - 4\right)$

= $\left(x + 6\right) \left(x - 6\right) \left(x - 4\right)$