Answer
$-2\sqrt[]{x}$
Work Step by Step
Subtracting the coefficients and then copying the common radical expression, the given expression, $
3\sqrt[]{x}-5\sqrt[]{x}
,$ is equivalent to
\begin{align*}
&
(3-5)\sqrt[]{x}
\\&=
-2\sqrt[]{x}
.\end{align*}
Hence, the given expression simplifies to $
-2\sqrt[]{x}
$.