\(\sqrt{0}=0\)

\(\sqrt{9}=3\)

\(\sqrt{121}=11\)

\(\sqrt{16}-\sqrt{36}=4-6=-2\)

\(12\sqrt{100}+3\sqrt{25}=12⋅10+3⋅5=135\)

\(\sqrt{4}⋅\sqrt{36}=2⋅6=12\)

\((-7\sqrt{5})^2=(-7)^2⋅\sqrt{5}^2=49⋅5=245\text{.}\)

\((6\sqrt{3}-5)(6\sqrt{3}+5)=(6\sqrt{3})^2-5^2=36⋅3-25=108-25=83\text{.}\)

\((\sqrt{11})^2=11\text{.}\)

\(9(\sqrt{2})^2=9⋅2=18\text{.}\)

\(10\sqrt{11}+9\sqrt{11}=19\sqrt{11}\)

\(2\sqrt{3}⋅3\sqrt{5}=6\sqrt{15}\)

\({\sqrt{21} \over \sqrt{3}}=\sqrt{7}\)

\({2\sqrt{15} \over \sqrt{5}}=2⋅{\sqrt{15} \over \sqrt{5}}=2\sqrt{3}\)

\({12\sqrt{27} \over 4\sqrt{3}}={12 \over 4}⋅{\sqrt{27} \over \sqrt{3}}=3⋅\sqrt{9}=3⋅3=9\)