Question

помогите пожалуйста​

Answer 1

$1)\\8\sqrt3-5\sqrt{12}+4\sqrt{75}=8\sqrt3-5\cdot2\sqrt{3}+4\cdot5\sqrt{3}=8\sqrt3-10\sqrt{3}+20\sqrt{3}=18\sqrt{3}\\\\2)\\\frac{a-5}{a+2\sqrt{5a}+5}=\frac{a-5}{(\sqrt a)^2+2\sqrt{5a}+(\sqrt5)^2}=\frac{(\sqrt a)^2-(\sqrt5)^2}{(\sqrt a)^2+2\sqrt{5a}+(\sqrt5)^2}=\frac{(\sqrt a-\sqrt5)(\sqrt a+\sqrt5)}{(\sqrt a+\sqrt5)^2}=\frac{\sqrt a-\sqrt5}{\sqrt a+\sqrt5}$