## Elementary Algebra

The negative exponent rule states that for every nonzero number $a$ and integer $n$, $a^{-n}=\frac{1}{a^n}$ We use this rule to rewrite the expression as $\frac{1}{\frac{1}{y^3}}$. We rewrite this fraction as a division problem: $\frac{1}{1}\div\frac{1}{y^3}$ To divide fractions, we multiply by the reciprocal: $\frac{1}{1}\times\frac{y^3}{1}=y^3$ The simplified form of the original expression is not $y^{-3}$