Question

[Lê Gia Bảo]

4/2*6+4/6*10+4/10*14+4*/14*18+4/18*22

Answer 1

[Akai Haruma]

Lời giải:
$\frac{4}{2\times 6}+\frac{4}{6\times 10}+\frac{4}{10\times 14}+\frac{4}{14\times 18}+\frac{4}{18\times 22}$

$=\frac{6-2}{2\times 6}+\frac{10-6}{6\times 10}+\frac{14-10}{10\times 14}+\frac{18-14}{14\times 18}+\frac{22-18}{18\times 22}$

$=\frac{1}{2}-\frac{1}{6}+\frac{1}{6}-\frac{1}{10}+\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+\frac{1}{18}-\frac{1}{22}$

$=\frac{1}{2}-\frac{1}{22}=\frac{20}{44}=\frac{5}{11}$