Answer
$\frac{x+2}{(1+x)^{3/2}}$
Work Step by Step
We factor out $(1+x)^{-1/2}$, remembering that $(1+x)=(1+x)^{-1/2}*(1+x)^{1/2}$:
$\displaystyle \frac{2(1+x)^{1/2}-x(1+x)^{-1/2}}{1+x}=\frac{(1+x)^{-1/2}[2(1+x)-x]}{1+x}=\frac{x+2}{(1+x)^{3/2}}$