\(\sqrt{20}=\sqrt{4}⋅\sqrt{5}=2\sqrt{5}\text{.}\)

\(-3\sqrt{28}=-3⋅\sqrt{4}⋅\sqrt{7}=-3⋅2⋅\sqrt{7}=-6\sqrt{7}\text{.}\)

\(\sqrt{\frac{1}{49}}={\sqrt{1} \over \sqrt{49}}=\frac{1}{7}\text{.}\)

\(\sqrt{\frac{17}{100}}={\sqrt{17} \over \sqrt{100}}={\sqrt{17} \over 10}=\frac{1}{10}\sqrt{17}\text{.}\)

\(\sqrt{500}+\sqrt{45}=\sqrt{100}⋅\sqrt{5}+\sqrt{9}⋅\sqrt{5}=10\sqrt{5}+3\sqrt{5}\text{.}\)

\(10\sqrt{5}+3\sqrt{5}=13\sqrt{5}\text{.}\)

\(3\sqrt{20}-4\sqrt{500}=3⋅\sqrt{4}⋅\sqrt{5}-4⋅\sqrt{100}⋅\sqrt{5}\text{.}\)

\(3⋅2⋅\sqrt{5}-4⋅10⋅\sqrt{5}=6\sqrt{5}-40\sqrt{5}=-34\sqrt{5}\text{.}\)

\({5 \over 3\sqrt{2}}={5 \over 3\sqrt{2}}⋅{\sqrt{2} \over \sqrt{2}}={5\sqrt{2} \over 3⋅2}=\frac{5}{6}\sqrt{2}\text{.}\)

\(\sqrt{\frac{49}{95}}={\sqrt{49} \over \sqrt{95}}={7 \over \sqrt{95}}⋅{\sqrt{95} \over \sqrt{95}}={7\sqrt{95} \over 95}=\frac{7}{95}\sqrt{95}\text{.}\)

\(\sqrt{1\frac{5}{7}}=\sqrt{\frac{12}{7}}={\sqrt{12} \over \sqrt{7}}⋅{\sqrt{7} \over \sqrt{7}}={\sqrt{84} \over 7}=\frac{1}{7}\sqrt{84}=\frac{1}{7}⋅2⋅\sqrt{21}=\frac{2}{7}\sqrt{21}\text{.}\)