Question

mong ai đó lướt qua thì hãy giúp tôi ạ

đề khó quá

Answer 1

câu b bài 1 mn ơi

 

Answer 2

Bài 1: b) 

\(\dfrac{\sqrt{30}-\sqrt{2}}{\sqrt{8-\sqrt{15}}}-\sqrt{8-\sqrt{49+8\sqrt{3}}}=\dfrac{\sqrt{2}\left(\sqrt{30}-\sqrt{2}\right)}{\sqrt{2}\sqrt{8-\sqrt{15}}}-\sqrt{8-\sqrt{48+2.4\sqrt{3}.1+1}}\)

\(=\dfrac{2\sqrt{15}-2}{\sqrt{15-2\sqrt{15}+1}}-\sqrt{8-\sqrt{\left(4\sqrt{3}+1\right)^2}}\)

\(=\dfrac{2\sqrt{15}-2}{\sqrt{\left(\sqrt{15}-1\right)^2}}-\sqrt{7-4\sqrt{3}}\)

\(=\dfrac{2\sqrt{15}-2}{\left|\sqrt{15}-1\right|}-\sqrt{4-2.2.\sqrt{3}+3}\)

\(=\dfrac{2\sqrt{15}-2}{\sqrt{15}-1}-\sqrt{\left(2-\sqrt{3}\right)^2}\)

\(=\dfrac{2\left(\sqrt{15}-1\right)}{\sqrt{15}-1}-\left|2-\sqrt{3}\right|\)

\(=2-\left(2-\sqrt{3}\right)=\sqrt{3}\)