a: \(=\sqrt{9\cdot6}=3\sqrt{6}\)
b: \(=\sqrt{36\cdot3}=6\sqrt{3}\)
c: \(=\dfrac{1}{10}\cdot\sqrt{10000\cdot2}=\dfrac{1}{10}\cdot100\cdot\sqrt{2}=10\sqrt{2}\)
d: \(=-\dfrac{1}{20}\cdot\sqrt{14400\cdot2}=-\dfrac{1}{20}\cdot120\cdot\sqrt{2}=-6\sqrt{2}\)
e: \(=\sqrt{7\cdot7\cdot9\cdot a^2}=21\left|a\right|\)