# How do you factor x² + x - 20?

Aug 1, 2015

Factor y = x^2 + x - 20

Ans: (x - 4)( x + 5)

#### Explanation:

Find 2 numbers knowing sum (1) and product (-20).
To find them, factor pairs of (-20) --> (-2, 10)(-4, 5). This sum is 1 = b.
Then, these 2 numbers are: -4 and 5.
y = (x - 4)(x + 5)