Answer
$-36\sqrt2$
Work Step by Step
Multiply the radicals to obtain:
\begin{align*}
&=4\sqrt2-8\sqrt{50}
\end{align*}
Factor the radicand so that one of the factors is a perfect square to obtain:
\begin{align*}
&=4\sqrt2-8\sqrt{25(2)}\\
\end{align*}
Simplifiy the radical by taking out the square root of the perfect square factor inside the radical sign to obtain:
\begin{align*}
&=4\sqrt2-8(5)\sqrt2\\
&=4\sqrt2-40\sqrt2\\
&=(4-40)\sqrt2\\
&=-36\sqrt2
\end{align*}
