C=$2\sqrt{a}$-$\sqrt{9a^3}$+$a^2\sqrt{\frac{4}{a}}$+$\frac{2}{a^2}$$\sqrt{25a^5}$ (a>0)
=$2\sqrt{a}$-$3a\sqrt{a}$+$a^2$$\frac{2}{\sqrt{a}}$+$\frac{2}{a^2}$$5a^2\sqrt{a}$
=$2\sqrt{a}$-$3a\sqrt{a}$+$a^2\frac{2\sqrt{a}}{a}$+$10\sqrt{a}$
=$2\sqrt{a}$-$3a\sqrt{a}$+$2a\sqrt{a}$+$10\sqrt{a}$
=$(2-3a+2a+10)\sqrt{a}$
=$(12-a)\sqrt{a}$