## Algebra 1: Common Core (15th Edition)

We use the rules of exponents to obtain: $(-5)^{2}$ - $(0.5)^{-2}$ = $(-5)^{2}$ - $(\frac{1}{2})^{-2}$ = 25 - $(\frac{1^{-2}}{2^{-2}})$ = 25 - $2^{2}$ = 25 -4 = 21