\(\frac{2}{3}+\frac{6}{5}+\frac{9}{10}+\frac{14}{15}+\frac{20}{21}+\frac{27}{28}+\frac{35}{36}+\frac{44}{45}+\frac{44}{55}\)
\(\frac{2}{3}x\frac{5}{6}x\frac{9}{10}x\frac{14}{15}x\frac{20}{21}x\frac{27}{28}\)
Tính bằng cách thuận tiện nhất:
\(\frac{1}{10}+\frac{2}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)
\(x+\frac{3+\frac{3}{20}+\frac{3}{13}+\frac{3}{2013}}{5+\frac{5}{20}+\frac{5}{13}+\frac{5}{2013}}=\frac{9}{2}\)
tìm x
tính bằng cách thuận tiện
\(\frac{1}{10}+\frac{2}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)
=...........................................................................................................................
=................................................................................................................
\(\frac{-5}{9}.\frac{3}{11}-\frac{5}{9}.\frac{10}{11}+\frac{5}{9}.\frac{10}{11}+\frac{5}{9}.\frac{2}{11}\)
\(\frac{10+\frac{9}{2}+\frac{8}{3}+\frac{7}{4}+ \frac{6}{5}+\frac{5}{6}+\frac{4}{7}+\frac{3}{8}+\frac{2}{9}+\frac{1}{10}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}+\frac{1}{11}}\)
tính ( theo mẫu ) :
\(a,\frac{9}{10}\cdot\frac{5}{6}\) \(b,\frac{6}{25}:\frac{21}{20}\)\(c,\frac{40}{7}\cdot\frac{14}{5}\)\(d,\frac{17}{13}:\frac{51}{26}\)
Mẫu : a, \(\frac{9}{10}\cdot\frac{5}{6}=\frac{9\cdot5}{10\cdot6}=\frac{3\cdot3\cdot5}{5\cdot2\cdot3\cdot2}=\)3*3*5 / 5* 2* 3 * 2 = \(\frac{3}{4}\)
\(\frac{1}{5}+\frac{4}{10}+\frac{9}{15}+\frac{16}{20}+\frac{25}{25}+\frac{36}{30}+\frac{49}{35}+\frac{64}{40}+\frac{81}{45}\)=?
Tính nhanh \(\frac{1}{5}+\frac{4}{10}+\frac{9}{15}+\frac{16}{20}+\frac{36}{30}+\frac{64}{40}+\frac{81}{45}\)