# How do you factor a^2b + 2ab - 15b?

Mar 26, 2018

$b \left(a + 5\right) \left(a - 3\right)$

#### Explanation:

First factor $b$ from every term

$b \left({a}^{2} + 2 a - 15\right)$

Then factorize the quadratic knowing that the factors of 15 are 15,1 and 3,5. The last two sum to 2 (5-3) so this is the correct pair

$b \left(a + 5\right) \left(a - 3\right)$