Question

How do you factor `r^2+12r+27`?

Answer 1

`r^2+12r+27 = (r+9)(r+3)`

Explanation:

Find a pair of factors of `27` whose sum is `12`:

`9 xx 3 = 27` works, so:

`r^2+12r+27 = (r+9)(r+3)`