# Math Help - Factor pairs

1. ## Factor pairs

How can finding the factor pairs of the constant in a trinomial help me factor the trinomial???

2. ## Re: Factor pairs

If you are given a quadratic in the form:

$x^2+ax+b$

Finding the factor pair of b whose sum is a, will easily allow you to factor the quadratic.

Suppose $b=cd$ where $a=c+d$, then we may write:

$x^2+ax+b=(x+c)(x+d)$

$ax^2+bx+c$
we want to find the factor pair of $ac$ whose sum is $b$.