Rút gon C= $\frac{150}{5×8}$+ $\frac{150}{8×11}$+ $\frac{150}{11×114}$+....+ $\frac{150}{47×50}$

Đáp án:

$C=9$

Giải thích các bước giải:

Ta có :

$C=\frac{150}{5.8}+\frac{150}{8.11}+\frac{150}{11.14}+.....+\frac{150}{47.50}$

→ $\frac{C}{50}=\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+.....+\frac{3}{47.50}$

→ $\frac{C}{50}=\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+.....+\frac{1}{47}-\frac{1}{50}$

→ $\frac{C}{50}= \frac{1}{5}-\frac{1}{50}$

→ $\frac{C}{50}=\frac{9}{50}$

→ $C=9$