Tính các tổng sau một cách hợp lí: ( 1/4 +3/4+2/8)+(5-/13+-8/13)

* Hướng dẫn giải

$a)\left(\frac{1}{4}+\frac{3}{4}+\frac{2}{8}\right)+\left(\frac{-5}{13}+\frac{8}{13}\right)=\frac{2}{8}$

$\begin{array}{l}b)\left(\frac{-7}{31}+\frac{7}{31}\right)+\left(\frac{24}{19}+\frac{-5}{19}\right)+\frac{1}{15}=\frac{16}{15}\\ \\ c)\left(\frac{-46}{43}+\frac{3}{43}\right)+\left(\frac{5}{17}+\frac{11}{17}+\frac{1}{17}\right)=0\\ \\ d)\left(\frac{21}{31}+\frac{10}{31}\right)+\left(\frac{44}{53}+\frac{9}{53}\right)+\frac{-16}{7}=\frac{-2}{7}\\ \\ e)\left(\frac{15}{16}+\frac{-15}{16}\right)+\left(\frac{13}{33}+\frac{7}{33}+\frac{10}{33}+\frac{3}{33}\right)=1\end{array}$