Đáp án D

Giải thích 

Chu vi hình vuông là :

\(\frac{3}{8}\times4=\frac{3}{2}\)( dm )

Diện tích hình vuông là :

\(\frac{3}{8}\times\frac{3}{8}=\frac{9}{64}\)( dm² )

Đáp số : .... 

a) \(E=2\sqrt{40\sqrt{12}}+3\sqrt{5\sqrt{48}}-2\sqrt{\sqrt{75}}-4\sqrt{15\sqrt{27}}.\)

  \(=8\sqrt{5\sqrt{3}}+6\sqrt{5\sqrt{3}}-2\sqrt{5\sqrt{3}-12\sqrt{5\sqrt{3}}}\)

  \(=0\)

b) \(F=\frac{1}{\sqrt{3}}+\frac{1}{3\sqrt{2}}+\frac{1}{\sqrt{3}}\sqrt{\frac{5}{12}-\frac{1}{\sqrt{6}}}.\)

Vì \(=\frac{5}{12}-\frac{1}{\sqrt{6}}=\frac{5-2\sqrt{6}}{12}=\frac{\left(\sqrt{3}-\sqrt{2}\right)^2}{12}\)

\(\frac{1}{\sqrt{3}}+\frac{1}{2\sqrt{3}}=\frac{\sqrt{3}}{3}+\frac{\sqrt{2}}{6}=\frac{2\sqrt{3}+\sqrt{2}}{6}\)

Nên \(F=\frac{2\sqrt{3}+\sqrt{2}}{6}+\frac{1}{\sqrt{3}}\sqrt{\frac{\left(\sqrt{3}-\sqrt{2}\right)^2}{12}}=\frac{2\sqrt{3}+\sqrt{2}+\sqrt{3}-\sqrt{2}}{6}=\frac{3\sqrt{3}}{6}=\frac{\sqrt{3}}{2}\)

a)C=\(\frac{1}{\sqrt{3}+\sqrt{2}-\sqrt{6}}\)   -\(\frac{1}{\sqrt{3}+\sqrt{2}+\sqrt{6}}\)

=\(\frac{1+\sqrt{6}}{\sqrt{3}+\sqrt{2}}-\frac{1-\sqrt{6}}{\sqrt{3}+\sqrt{2}}\)

=\(\frac{1+\sqrt{6}-1+\sqrt{6}}{\sqrt{3}+\sqrt{2}}\)

=\(\frac{2\sqrt{6}}{\sqrt{3}+\sqrt{2}}\)

2,4,6,8,10,12,14,16,18,20......

còn nhiều lắm nha

hok tốt 

x * x = x2

chịu 😅

, \(A=\frac{\sqrt{7}-5}{2}-\frac{6-2\sqrt{7}}{4}+\frac{6}{\sqrt{7}-2}-\frac{5}{4+\sqrt{7}}\)

\(=\frac{2\sqrt{7}-10-6+2\sqrt{7}}{4}+\frac{6\left(\sqrt{7}+2\right)}{3}-\frac{5\left(4-\sqrt{7}\right)}{9}\)

\(=\frac{-16+4\sqrt{7}}{4}+\frac{18\sqrt{7}+36-20+5\sqrt{7}}{9}=-4+\sqrt{7}+\frac{23\sqrt{7}+16}{9}\)

b,\(B=\frac{2}{\sqrt{6}-2}+\frac{2}{\sqrt{6}+2}+\frac{5}{\sqrt{6}}=\frac{2\left(\sqrt{6}+2\right)+2\left(\sqrt{6}-2\right)}{2}+\frac{5\sqrt{6}}{6}\)

\(=\frac{12\sqrt{6}+5\sqrt{6}}{6}=\frac{17\sqrt{6}}{6}\)

70 l nha em

5A nha

hok tốt nha

lấy 90 : 18 là 5 nha

hok tốt

5 x 3 = 15!