Question

How do you factor completely `x^2 – 3x – 18`?

Answer 1

`x^2-3x-18 = (x-6)(x+3)`

Explanation:

Find a pair of factors of `18` which differ by `3`. The pair `6, 3` works, hence we find:

`x^2-3x-18=x^2-(6-3)x-(6*3)=(x-6)(x+3)`