\(\sqrt{0}=0\)

\(\sqrt{9}=3\)

\(\sqrt{121}=11\)

\(\sqrt{4}-\sqrt{9}=2-3=-1\)

\(10\sqrt{121}+9\sqrt{4}=10⋅11+9⋅2=128\)

\(\sqrt{9}⋅\sqrt{81}=3⋅9=27\)

\((6\sqrt{7})^2=6^2⋅\sqrt{7}^2=36⋅7=252\text{.}\)

\((9\sqrt{4}+2)(9\sqrt{4}-2)=(9\sqrt{4})^2-2^2=81⋅4-4=324-4=320\text{.}\)

\((\sqrt{2})^2=2\text{.}\)

\(-2(\sqrt{3})^2=-2⋅3=-6\text{.}\)

\(9\sqrt{11}-4\sqrt{11}=5\sqrt{11}\)

\(5\sqrt{19}⋅4\sqrt{2}=20\sqrt{38}\)

\({\sqrt{30} \over \sqrt{6}}=\sqrt{5}\)

\({28\sqrt{35} \over 7\sqrt{5}}={28 \over 7}⋅{\sqrt{35} \over \sqrt{5}}=4\sqrt{7}\)

\({35\sqrt{28} \over 5\sqrt{7}}={35 \over 5}⋅{\sqrt{28} \over \sqrt{7}}=7⋅\sqrt{4}=7⋅2=14\)