# How do you know if # 25b^2 − 45b − 81# is a perfect square trinomial and how do you factor it?

##### 1 Answer

May 14, 2018

It's not a perfect square trinomial

#### Explanation:

A perfect square is expanded as

So, you must check if you have two perfect squares with positive sign (

In your case, you only have one perfect square, which is