# What is the difference of two squares method of factoring?

##### 1 Answer
Mar 27, 2018

There's a single formula which refers to "difference of squares":

${a}^{2} - {b}^{2} = \left(a - b\right) \left(a + b\right)$

If we use FOIL we can prove that. Difference of squares method would refer to doing something like the following:

${x}^{2} - 1 = \left(x - 1\right) \left(x + 1\right)$
${x}^{2} - 4 = \left(x - 2\right) \left(x + 2\right)$

Or even the double application here
${x}^{4} - 16 = {\left({x}^{2}\right)}^{2} - {4}^{2} = \left({x}^{2} - 4\right) \left({x}^{2} + 4\right) = \left(x - 2\right) \left(x + 2\right) \left({x}^{2} + 4\right)$