162

$\frac{2}{\sqrt{x}}=2\cdot\ \frac{1}{\sqrt{x}}=2\sqrt{x^{-1}}=2x^{-\frac{1}{2}}$

$\frac{x^2}{3\sqrt{x}}=\frac{1}{3}\cdot\frac{x^2}{\sqrt{x}}=\frac{1}{3}x^2\cdot x^{-\frac{1}{2}}=\frac{1}{3}x^{\frac{3}{2}}$
c)

$\frac{3}{4x\sqrt{x}}=\frac{3}{4}\cdot\frac{1}{x\sqrt{x}}=\frac{3}{4}x^{-1}x^{-\frac{1}{2}}=\frac{3}{2}x^{-\frac{3}{2}}$

$\frac{2\sqrt{x}}{5x}=\frac{2}{5}\cdot\frac{\sqrt{x}}{x}=\frac{2}{5}\cdot x^{-1}\cdot x^{\frac{1}{2}}=\frac{2}{5}x^{-\frac{1}{2}}$