1/2:1/3:1/4:1/5
=1/2x3:1/4:1/5
=3/2x4:1/5
=6:1/5
=6x5
=30
\(\frac{1}{2}:\frac{1}{3}:\frac{1}{4}:\frac{1}{5}=\frac{1}{2}.\frac{3}{1}:\frac{1}{4}:\frac{1}{5}=\frac{3}{2}.\frac{4}{1}:\frac{1}{5}=6.5=30\)
\(\frac{1}{2}-\frac{1}{3}-\frac{2}{3}+\frac{1}{4}+\frac{2}{4}+\frac{3}{4}-\frac{1}{5}-\frac{2}{5}-\frac{3}{5}-\frac{4}{5}+...+\frac{1}{10}+\frac{2}{10}+\frac{3}{10}+...+\frac{9}{10}\)\(+\)\(\frac{9}{10}\)
\(\frac{1}{1×2}+\frac{1}{2×3}\: +\frac{1}{3×4}\: +\frac{1}{4×5}+\frac{1}{5×6}\: +\frac{1}{6×7}+\frac{1}{7×8}+\frac{1}{8×9}\: =?\)
a) \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}\) b) \(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
c) \(\frac{1}{5}+\frac{1}{10}+\frac{1}{20}+\frac{1}{40}+...............+\frac{1}{1280}\) d) \(\frac{2}{3}+\frac{2}{6}+\frac{2}{12}+\frac{2}{24}+\frac{2}{48}+\frac{2}{96}+\frac{2}{192}\)
e) \(1+\frac{5}{4}+\frac{5}{8}+\frac{5}{16}+\frac{5}{32}+\frac{5}{64}\) f) \(\frac{3}{2}+\frac{3}{8}+\frac{3}{32}+\frac{3}{128}+\frac{3}{512}\)
g) \(3+\frac{3}{5}+\frac{3}{25}+\frac{3}{125}+\frac{3}{625}\)
B1:Tính
a)\(3\frac{4}{7}x2\frac{4}{5}\)
b)\(\frac{4}{5}:\frac{1}{2}+\frac{17}{3}\)
c)\(5\frac{1}{3}-2\frac{1}{6}\)
d)\(4\frac{1}{2}:2\frac{1}{4}\)
a)Tính bằng cách thuận tiện nhất :
\(\frac{1}{2}x\frac{1}{3}+\frac{1}{3}x\frac{1}{4}+\frac{1}{4}x\frac{1}{5}+\frac{1}{5}x\frac{1}{6}\)
b) Tính :
\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)\)
$\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}=$ cần gấp
Bài 1 : tính theo cách hợp lý nhất
\(\frac{6}{11}+\frac{1}{3}+\frac{5}{11}\)
Bài 2 : Tính bằng cách nhanh nhất
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}\)
Bài 3 : Tính nhanh
a,\(\frac{3}{2}\times\frac{4}{5}\times\frac{2}{3}\)
b,\(\frac{6}{7}\times\subset\frac{5}{3}\times\frac{7}{6}\supset\)
Bài 4 : Tính nhanh
a,\(\frac{2}{5}\times\frac{1}{4}+\frac{3}{4}\times\frac{2}{5}\)
b,\(\frac{6}{11}\div\frac{2}{3}+\frac{5}{11}\div\frac{2}{3}\)
\(A=\)\(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}\)
\(B=\frac{2}{5}.\frac{15}{4}:\frac{5}{16}+\frac{1}{2}\)
\(\frac{75}{100}+\frac{18}{21}+\frac{19}{23}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}=\)
\(4\frac{2}{5}+5\frac{6}{9}+2\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+\frac{2}{7\cdot9}+.....+\frac{2}{41\cdot43}\)
Bài 1:Tính nhanh:
a,\(\frac{2}{3}+\frac{4}{6}+\frac{6}{3}\)
b,\(\frac{3}{4}+\frac{6}{8}+\frac{18}{12}\)
Bài 2:Tính:
a,\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\)
b,\(\frac{1}{2}+\frac{1}{3}+\frac{1}{5}+\frac{1}{7}\)