Question

Answer 1

\(a,VT=\dfrac{\sqrt{xy}\left(\sqrt{x}-\sqrt{x}\right)}{\sqrt{x}-\sqrt{y}}=\sqrt{xy}=VP\\ \)

\(b=\dfrac{\sqrt{4}}{\sqrt{\left(1-\sqrt{7}\right)^2}}-\dfrac{\sqrt{4}}{\sqrt{\left(1+\sqrt{7}\right)^2}}=\dfrac{2}{\left|1-\sqrt{7}\right|}-\dfrac{2}{\left|1+\sqrt{7}\right|}=\dfrac{2}{\sqrt{7}-1}-\dfrac{2}{1+\sqrt{7}}=\dfrac{2\left(1+\sqrt{7}\right)-2\left(\sqrt{7}-1\right)}{7-1}=\dfrac{2+2\sqrt{7}-2\sqrt{7}+2}{6}=\dfrac{4}{6}=\dfrac{2}{3}=VP\)