\(\sqrt{500}=\sqrt{100}⋅\sqrt{5}=10\sqrt{5}\text{.}\)

\(-2\sqrt{18}=-2⋅\sqrt{9}⋅\sqrt{2}=-2⋅3⋅\sqrt{2}=-6\sqrt{2}\text{.}\)

\(\sqrt{\frac{4}{49}}={\sqrt{4} \over \sqrt{49}}=\frac{2}{7}\text{.}\)

\(\sqrt{1\frac{7}{16}}=\sqrt{\frac{23}{16}}={\sqrt{23} \over \sqrt{16}}={\sqrt{23} \over 4}=\frac{1}{4}\sqrt{23}\text{.}\)