Question

Thu gọn Chỉ cần ra đáp án thôi ạ,e mình lm sợ sai ý:'(((

Answer 1

4.

$\sqrt{7-2\sqrt{10}}-\sqrt{7+2\sqrt{10}}$

$=\sqrt{(\sqrt{5}-\sqrt{2})^2}-\sqrt{(\sqrt{5}+\sqrt{2})^2}$

$=|\sqrt{5}-\sqrt{2}|-|\sqrt{5}+\sqrt{2}|$

$=\sqrt{5}-\sqrt{2}-(\sqrt{5}+\sqrt{2})=-2\sqrt{2}$

5.
$\sqrt{7-4\sqrt{3}}-\sqrt{4-2\sqrt{3}}$

$=\sqrt{(2-\sqrt{3})^2}-\sqrt{(\sqrt{3}-1)^2}$

$=|2-\sqrt{3}|-|\sqrt{3}-1|$

$=2-\sqrt{3}-(\sqrt{3}-1)=3-2\sqrt{3}$

 

Answer 2

6. 

$\sqrt{11-6\sqrt{2}}+\sqrt{11+6\sqrt{2}}=\sqrt{(3-\sqrt{2})^2}+\sqrt{(3+\sqrt{2})^2}$

$=|3-\sqrt{2}|+|3+\sqrt{2}|=3-\sqrt{2}+3+\sqrt{2}=6$

7.

$\sqrt{49-20\sqrt{6}}+\sqrt{106+20\sqrt{6}}$

$=\sqrt{(\sqrt{25}-\sqrt{24})^2}+\sqrt{(\sqrt{100}+\sqrt{6})^2}$

$=|\sqrt{25}-\sqrt{24}|+|\sqrt{100}+\sqrt{6}|$

$=\sqrt{25}-\sqrt{24}+\sqrt{100}+\sqrt{6}=15-\sqrt{6}$

 

Answer 3

8.

$\sqrt{13-4\sqrt{10}}+\sqrt{13+4\sqrt{10}}$

$=\sqrt{(\sqrt{8}-\sqrt{5})^2}+\sqrt{(\sqrt{8}+\sqrt{5})^2}$

$=|\sqrt{8}-\sqrt{5}|+|\sqrt{8}+\sqrt{5}|$

$=\sqrt{8}-\sqrt{5}+\sqrt{8}+\sqrt{5}=2\sqrt{8}=4\sqrt{2}$

P/s: Nếu bạn muốn check kết quả, có 1 cách rất đơn giản là bấm máy.