# How do you multiply (x - 10)(x + 10) ?

${x}^{2} - 100$.
Recall that $\left(a - b\right) \left(a + b\right) = {a}^{2} - {b}^{2}$
Hence, $\left(x - 10\right) \left(x + 10\right) = {x}^{2} - {10}^{2} = {x}^{2} - 100$-