Answer
$\frac{r-2}{5(\sqrt{r}-\sqrt{2})}$
Work Step by Step
We simplify the fraction by multiplying through by $\sqrt{r}-\sqrt{2}$ and using the fact that $(a-b)(a+b)=a^2-b^2$:
$\displaystyle \frac{\sqrt{r}+\sqrt{2}}{5}=\frac{\sqrt{r}+\sqrt{2}}{5} \displaystyle *\frac{\sqrt{r}-\sqrt{2}}{\sqrt{r}-\sqrt{2}}=\frac{r-2}{5(\sqrt{r}-\sqrt{2})}$
