If two terms in a binomial are perfect squares separated by subtraction, then you can easily factor them.

For example, a² is a perfect square b² is also a perfect square

The difference of the two perfect squares, that is, a² − b² or b² − a² is called difference of two squares and can be factorized as follows

Difference of two squares

• a² − b² = (a − b) (a + b)
• x² − y² = (x − y) (x + y)
• m² − n² = (m − n) (m + n)