Factor x^2 - 9

Step by step

The question

Question: factor x² − 9.

Factor means: write it as a times, with brackets.

1 Two squares

This is one square take away another square.

x² is x squared.

9 is 3 squared.

A square minus a square is the plus bracket times the minus bracket.

So we get (x + 3)(x − 3).

2 Check

Let's check: we multiply it back out.

Each part of the first bracket times each part of the second.

We get x² − 9 again.

So (x + 3)(x − 3) is right!

Let's look back.

First: two squares.

Last: check.