# How do you factor  r^2 + 2r - 63?

Jan 28, 2017

${r}^{2} + 2 r - 63 = \left(r - 7\right) \left(r + 9\right)$

#### Explanation:

First notice that

${r}^{2} + 2 r - 63 = {r}^{2} + \left(9 - 7\right) r + \left(- 7\right) \left(9\right)$

Then

${r}^{2} + 2 r - 63 = \left(r - 7\right) \left(r + 9\right)$