ae giúp tớ voiii 2 câuu

Đáp án:

$a) P= \dfrac{\sqrt{5}}{2}\\ b) Q=-2.$

Giải thích các bước giải:

$a) P=\dfrac{\sqrt{15}-\sqrt{5}}{\sqrt{3}-1} - \dfrac{5 - 2\sqrt{5}}{2\sqrt{5}-4}\\ =\dfrac{\sqrt{5}(\sqrt{3}-1)}{\sqrt{3}-1} - \dfrac{\sqrt{5}(\sqrt{5} - 2)}{2(\sqrt{5}-2)}\\ =\sqrt{5} - \dfrac{\sqrt{5}}{2}\\ = \dfrac{\sqrt{5}}{2}\\ b) Q=\dfrac{3-2\sqrt{3}}{\sqrt{3}}+\dfrac{2+\sqrt{2}}{\sqrt{2}+1}-(\sqrt{2}+\sqrt{3})\\ =\dfrac{\sqrt{3}(\sqrt{3}-2)}{\sqrt{3}}+\dfrac{\sqrt{2}(\sqrt{2}+1)}{\sqrt{2}+1}-\sqrt{2}-\sqrt{3}\\ =\sqrt{3}-2+\sqrt{2}-\sqrt{2}-\sqrt{3}\\ =-2.$