Tính nhanh (13/18 1/71)-(13/18 70/71 5/11)

Lời giải:

\(\left( {\frac{{13}}{{18}} + \frac{1}{{71}}} \right) - \left( {\frac{{13}}{{18}} - \frac{{70}}{{71}} + \frac{5}{{11}}} \right)\)

\( = \frac{{13}}{{18}} + \frac{1}{{71}} - \frac{{13}}{{18}} + \frac{{70}}{{71}} - \frac{5}{{11}}\) 

\( = \left( {\frac{{13}}{{18}} - \frac{{13}}{{18}}} \right) + \left( {\frac{1}{{71}} + \frac{{70}}{{71}}} \right) - \frac{5}{{11}}\)

\( = 0 + 1 - \frac{5}{{11}} = \frac{6}{{11}}.\)