[tex]\it \sqrt{0,(4)}=\sqrt{\dfrac{4}{9}}=\dfrac{2}{3}\in\mathbb{Q}\\ \\ \\ \sqrt{0,016}=\sqrt{\dfrac{\ 16^{(4}}{1000}}=\sqrt{\dfrac{4}{250}}=\dfrac{\sqrt4}{\sqrt{25\cdot10}}=\dfrac{^{\sqrt{10})}2}{\ \ 5\sqrt{10}}=\dfrac{2\sqrt{10}^{(2}}{5\cdot10}=\dfrac{\sqrt{10}}{25}\not\in\mathbb{Q}[/tex]
