Answer
$2z-z^{3/2} -z^{2}$
Work Step by Step
$\begin{array}{ l l }
\begin{array}{l}
=( 2z^{1/2}\left( z^{1/2} -z\right) +z\left( z^{1/2} -z\right)\\
=2z^{1/2} z^{1/2} -2z^{1/2} z+zz^{1/2} -zz\\
\\
\end{array} & \mathrm{Apply\ the\ distributive\ property}\\
=2z^{1/2+1/2} -2z^{1/2+2/2} +z^{1/2+2/2} -z^{1+1} & \begin{array}{l}
\mathrm{Apply\ the\ rule}\\
a^{b} \cdot a^{c} =a^{b+c}
\end{array}\\
& \\
=2z^{2/2} -2z^{3/2} +z^{3/2} -z^{2} & \mathrm{Add\ fractions.}\\
& \\
=2z-z^{3/2} -z^{2} & \mathrm{Simplify.}
\end{array}$
