e. $(\frac{2021}{2020}-\frac{2015}{2016})(\frac{1}{3}-\frac{1}{4}-\frac{1}{12})$
= $(\frac{2021}{2020}-\frac{2015}{2016}).$$\frac{4-3-1}{12}$
= $(\frac{2021}{2020}-\frac{2015}{2016}).0$
= $0^{}$
f. $\frac{-5}{7}.\frac{2}{11}+(\frac{-5}{7}).\frac{4}{11}+\frac{5}{7}.(\frac{-5}{11})$
= $\frac{-5}{7}.\frac{2}{11}+(\frac{-5}{7}).\frac{4}{11}+(\frac{-5}{7}).\frac{5}{11}$
= $\frac{-5}{7}.(\frac{2+4+5}{11})$
= $\frac{-5}{7}.$ $\frac{11}{11}$
= $\frac{-5}{7}$
Chúc bạn học tốt !!!!!!
