Thực hiện phép tính: \(\frac{{ - 7}}{{25}}.\frac{{11}}{{13}} + \frac{{ - 7}}{{25}}.\frac{2}{{13}} - \frac{{18}}{{25}}\)

* Hướng dẫn giải

Ta có:

\(\frac{{ - 7}}{{25}}.\frac{{11}}{{13}} + \frac{{ - 7}}{{25}}.\frac{2}{{13}} - \frac{{18}}{{25}} \\= \frac{{ - 7}}{{25}}\left( {\frac{{11}}{{13}} + \frac{2}{{13}}} \right) - \frac{{18}}{{25}} \\= \frac{{ - 7}}{{25}}.\frac{{13}}{{13}} - \frac{{18}}{{25}} \\= - \frac{{18}}{{25}} + \frac{{ - 18}}{{25}} \\= \frac{{ - 7 + ( - 18)}}{{25}}\\ = \frac{{ - 25}}{{25}} = - 1\)