Question

АЛГЕБРА ПОМОГИТЕ ДАЮ 50 БАЛЛОВ
1,2,3 СДЕЛАЙТЕ

Answer 1

$\displaystyle \tt 1). \ (2\sqrt{3}-\sqrt{2})^{2}=(2\sqrt{3})^{2}-2\cdot2\sqrt{3}\cdot\sqrt{2}+(\sqrt{2})^{2}=12-4\sqrt{6}+2=14-4\sqrt{6};\\\\\\2). \ A^{2}=\bigg(\frac{2\sqrt{7}}{7}\bigg)^{2}=\frac{4\cdot7}{49}=\frac{4}{7}; \ \ \ \ \ \ \ \ \ \ \ B^{2}=\bigg(\frac{\sqrt{20}}{4}\bigg)^{2}=\frac{20}{16};\\\\{} \ \ \ \ \frac{4}{7}<\frac{20}{16} \ \ \ \Rightarrow \ \ \ \ A^{2}<B^{2} \ \ \ \ \Rightarrow \ \ \ \ A<B$

$\displaystyle \tt 3). \ \frac{9-a}{\sqrt{a}-3}=-\frac{(\sqrt{a})^{2}-3^{2}}{\sqrt{a}-3}=-\frac{(\sqrt{a}-3)(\sqrt{a}+3)}{\sqrt{a}-3}=-\sqrt{a}-3;$