Giúp mình với ạ

=349

\(A=2\sqrt{40\sqrt{12}}-2\sqrt{\sqrt{75}}-3\sqrt{5\sqrt{48}}\)

\(=2\sqrt{40\sqrt{4.3}}-2\sqrt{\sqrt{25.3}}-3\sqrt{5\sqrt{16.3}}\)

\(=2\sqrt{80\sqrt{3}}-2\sqrt{5\sqrt{3}}-3\sqrt{20\sqrt{3}}\)

\(=2\sqrt{16.5\sqrt{3}}-2\sqrt{5\sqrt{3}}-3\sqrt{4.5\sqrt{3}}\)

\(=8\sqrt{5\sqrt{3}}-2\sqrt{5\sqrt{3}}-6\sqrt{5\sqrt{3}}=0\)

\(B=\left(3\sqrt{11}-3\sqrt{2}-\sqrt{11}\right)\sqrt{11}+3\sqrt{22}\)

\(=\left(2\sqrt{11}-3\sqrt{2}\right)\sqrt{11}+3\sqrt{22}\)

\(=2\sqrt{11}.\sqrt{11}-3\sqrt{2}.\sqrt{11}+3\sqrt{22}=22\)

mình làm được rồi, các bạn không cần làm nữa đâu

a) \(\sqrt{19-6\sqrt{2}}=3\sqrt{2}-1\)

b) \(\sqrt{11-6\sqrt{2}}=3-\sqrt{2}\)

d) \(\sqrt{21+12\sqrt{3}}=2\sqrt{3}+3\)

e) \(\sqrt{57-40\sqrt{2}}=4\sqrt{2}-5\)

a: \(\left(3+\sqrt{5}\right)^2=14+6\sqrt{5}\)

\(\left(2\sqrt{2}+\sqrt{6}\right)^2=14+4\sqrt{12}\)

mà \(6\sqrt{5}< 4\sqrt{12}\)

nên \(3+\sqrt{5}< 2\sqrt{2}+\sqrt{6}\)

c: \(\sqrt{14}-\sqrt{13}=\dfrac{1}{\sqrt{14}+\sqrt{13}}\)

\(\sqrt{12}-\sqrt{11}=\dfrac{1}{\sqrt{12}+\sqrt{11}}\)

mà \(\dfrac{1}{\sqrt{14}+\sqrt{13}}< \dfrac{1}{\sqrt{12}+\sqrt{11}}\)

nên \(\sqrt{14}-\sqrt{13}< \sqrt{12}-\sqrt{11}\)

cho mot sonco 11

I don't know

Áp dụng: \(\sin a=\cos\left(90-a\right);\text{ }\sin^2a+\cos^2a=1\Rightarrow\sin^2a+\sin^2\left(90-a\right)=1\)

\(\sin^210+\sin^220+...+\sin^280=\left(\sin^210+\sin^280\right)+\left(\sin^220+\sin^270\right)+...+\left(\sin^240+\sin^250\right)\)

\(=1+1+1+1=4\)

`6/(sqrt11+sqrt5)-(11+sqrt11)/(sqrt11+1)+1/(2sqrt5)`

`=(6(sqrt11-sqrt5))/(11-5)-(sqrt11(sqrt11+1))/(sqrt11+1)+sqrt5/10`

`=sqrt11-sqrt5-sqrt11+sqrt5/10`

`=sqrt5/10-sqrt5=(-9sqrt5)/10`

\(\dfrac{6}{\sqrt{11}+\sqrt{5}}-\dfrac{11+\sqrt{11}}{\sqrt{11}+1}+\dfrac{1}{2\sqrt{5}}\)

\(=\sqrt{11}-\sqrt{5}-\sqrt{11}+\dfrac{1}{10}\sqrt{5}\)

\(=-\dfrac{9}{10}\sqrt{5}\)