#### Answer

$\sqrt{\dfrac{1}{5}}=\dfrac{\sqrt{5}}{5}$

#### Work Step by Step

$\sqrt{\dfrac{1}{5}}$
Rewrite this fraction as $\dfrac{\sqrt{1}}{\sqrt{5}}$:
$\sqrt{\dfrac{1}{5}}=\dfrac{\sqrt{1}}{\sqrt{5}}=\dfrac{1}{\sqrt{5}}=...$
Multiply the fraction by $\dfrac{\sqrt{5}}{\sqrt{5}}$ and simplify:
$...=\dfrac{1}{\sqrt{5}}\cdot\dfrac{\sqrt{5}}{\sqrt{5}}=\dfrac{\sqrt{5}}{\sqrt{5^{2}}}=\dfrac{\sqrt{5}}{5}$