Question

Tính nhanh :  10/11 :(2/3x5+2/5x7+2/9x11 )

 

Answer 1

\(\frac{10}{11}\div\left(\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+\frac{2}{9\cdot11}\right)\)

\(=\frac{10}{11}\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{9}-\frac{1}{11}\right)\)

\(=\frac{10}{11}\left(\frac{1}{3}-\frac{1}{7}+\frac{1}{9}-\frac{1}{11}\right)\)

=> sai đề