Rút gọn

A

- Hướng dẫn giải

Đáp án A

$$\begin{gathered} N=\frac{{\displaystyle \frac{4}{17}}-{\displaystyle \frac{4}{49}}-{\displaystyle \frac{4}{131}}}{{\displaystyle \frac{3}{17}}-{\displaystyle \frac{3}{49}}-{\displaystyle \frac{3}{131}}}=\frac{4.{\displaystyle \frac{1}{17}}-4.{\displaystyle \frac{1}{49}}-4.{\displaystyle \frac{1}{131}}}{3.{\displaystyle \frac{1}{17}}-3.{\displaystyle \frac{1}{49}}-3.{\displaystyle \frac{1}{131}}} \\ =\frac{4\left({\displaystyle \frac{1}{17}}-{\displaystyle \frac{1}{49}}-{\displaystyle \frac{1}{131}}\right)}{3\left(\frac{1}{17}-\frac{1}{49}-\frac{1}{131}\right)}=\frac{4}{3} \end{gathered}$$