$\frac{1}{56}$+$\frac{2}{80}$+$\frac{3}{130}$+$\frac{4}{221}$+$\frac{5}{374}$
=$\frac{1}{7.8}$+$\frac{2}{8.10}$+$\frac{3}{10.13}$+$\frac{4}{13.17}$+$\frac{5}{17.22}$
=$\frac{1}{7}$-$\frac{2}{8}$+$\frac{1}{8}$-$\frac{1}{10}$+$\frac{1}{10}$-$\frac{1}{13}$+$\frac{1}{13}$-$\frac{1}{17}$+$\frac{1}{17}$-$\frac{1}{22}$
=$\frac{1}{7}$-$\frac{1}{22}$
=$\frac{15}{154}$
Bạn cho mình câu trả lời hay nhất nhé!!!!!!!!!
@wataru
