2/5+2/10+2/20+2/40+2/80
32/80+16/80+8/80+4/80+2/80
48/80+8/80+4/80+2/80
56/80+4/80+2/80
60/80+2/80
31/40
\(\frac{2}{5}+\frac{2}{10}+\frac{2}{20}+\frac{2}{40}+\frac{2}{80}\)
\(=\frac{2}{5}+\frac{1}{5}+\frac{1}{10}+\frac{1}{20}+\frac{1}{40}\)
\(=\frac{16}{40}+\frac{8}{40}+\frac{4}{40}+\frac{2}{40}+\frac{1}{40}\)
\(=\frac{31}{40}\)
Học tốt
\(\frac{2}{5}+\frac{1}{10}+\frac{2}{20}+\frac{2}{40}+\frac{2}{80}\)
\(=\frac{2}{5}+\frac{1}{5}+\frac{1}{10}+\frac{1}{20}+\frac{1}{40}\)
\(=\frac{16}{40}+\frac{8}{40}+\frac{4}{40}+\frac{2}{40}+\frac{1}{40}\)
\(=\frac{31}{40}\)
