Difference of two squares

Difference of two squares is a pattern that can be used to factor certain quadratic equations on the ACT math section. The default formula is that:

a² − b² = (a+b)(a−b). The terms in this formula can be either variables or constants. There is no center term because the two binomials are conjugates of each other.

When the difference of squares appears on the ACT, the a term is normally a variable and the b term is a constant. This means the left side of identity normally looks like: x² − 16.