Tính tổng ​\(\dfrac{5}{{19}} + \dfrac{{ - 7}}{{14}} + \dfrac{4}{{19}} + \dfrac{{10}}{{19}}\) bằng:

* Hướng dẫn giải

Ta có:

 \(\begin{array}{l}\dfrac{5}{{19}} + \dfrac{{ - 7}}{{14}} + \dfrac{4}{{19}} + \dfrac{{10}}{{19}}\\ = \left( {\dfrac{5}{{19}} + \dfrac{4}{{19}} + \dfrac{{10}}{{19}}} \right) + \dfrac{{ - 7}}{{14}}\\ = 1 + \left( { - \dfrac{1}{2}} \right)\\ = \dfrac{1}{2}\end{array}\)