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**Prove It** For starters, $\displaystyle \displaystyle \begin{align*} 3^3 = 27 \end{align*}$, not 9.

Also how did you magically turn $\displaystyle \displaystyle \begin{align*} y \end{align*}$ into $\displaystyle \displaystyle \begin{align*} y^{-1} \end{align*}$, $\displaystyle \displaystyle \begin{align*} x^{-3} \end{align*}$ into $\displaystyle \displaystyle \begin{align*} x^3 \end{align*}$ and $\displaystyle \displaystyle \begin{align*} (z + 1)^{-1} \end{align*}$ into $\displaystyle \displaystyle \begin{align*} z + 1 \end{align*}$?