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Bài giải
a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)
\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)
b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)
\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)
c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)
d, \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)
\(=1+1+1\)
\(=3\)
e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)
\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)
\(=1+1+1\)
\(=3\)
a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)
\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)
b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)
\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)
c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)
d, \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)
\(=1+1+1\)
\(=3\)
e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)
\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)
\(=1+1+1\)
\(=3\)
\(\frac{5}{12}-\frac{7}{32}:\frac{21}{16}\)
=\(\frac{5}{12}-\frac{7}{32}.\frac{16}{21}\)
=\(\frac{5}{12}-\frac{1}{6}\)
=\(\frac{5}{12}-\frac{2}{12}\)
=\(\frac{1}{4}\)
\(a)\frac{2}{5}+\frac{3}{10}-\frac{1}{2}\)
\(=\frac{4}{10}+\frac{3}{10}-\frac{5}{10}=\frac{1}{5}\)
\(b)\frac{8}{11}+\frac{8}{33}.\frac{3}{4}\)
\(=\frac{8}{11}+\frac{2}{11}=\frac{10}{11}\)
\(c)\frac{7}{9}.\frac{3}{14}:\frac{5}{8}\)
\(=\frac{1}{6}:\frac{5}{8}=\frac{4}{15}\)
\(d)\frac{5}{12}-\frac{7}{32}:\frac{21}{16}\)
\(=\frac{5}{12}-\frac{1}{6}=\frac{5}{12}-\frac{2}{12}=\frac{1}{4}\)
2/5 + 3/10 - 1/2
= 4/10 + 3/10 -5/10
=2/10
=1/5.
8/11 + 8/33 *3/4
=8/11 + 2/11
=10/11
7/9 *3/14 : 5/8
=1/3 *1/2 : 5/8
=1/6: 5/8
=1/3 * 4/5
=4/15
5/12 - 7/32 : 21/16
=5/12 - 1/6
=5/12 - 2/12
=1/4
5/12 -7/32 :21/16
\(=\frac{5}{12}-\frac{1}{6}\)
\(=\frac{1}{4}\)
5/12 - 7/32 : 21/16 = 5/12 - 112/672
= 280/672 - 112/672
= 168/672 = 1/4
7/9 x 3/14 : 5/8 = 1/6 : 5/8 = 4/15
5/12 - 7/32 : 21/16 = 5/12 - 1/6 = 1/4
\(=\dfrac{5}{12}-\dfrac{7}{32}\cdot\dfrac{16}{21}=\dfrac{5}{12}-\dfrac{1}{6}=\dfrac{5}{12}-\dfrac{2}{12}=\dfrac{1}{4}\)
\(\frac{7}{9}+\frac{6}{7}\times\frac{4}{5}=\frac{7}{9}+\frac{24}{35}=\frac{361}{315}\)
\(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{16}{15}=\frac{548}{345}\)
\(\frac{5}{8}\times\frac{4}{9}:\frac{2}{3}=\frac{5}{18}:\frac{2}{3}=\frac{5}{12}\)
\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{11}{24}\)
b,
\(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{4}{5}.\frac{8}{6}=\frac{21}{23}+\frac{16}{15}=1\frac{338}{345}\)
c,
\(\frac{5}{8}.\frac{4}{9}.\frac{3}{2}=\frac{5}{12}\)
d,
\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{13}{24}\)
chán thật
\(\frac{5}{12}-\frac{7}{32}:\frac{21}{6}\)
\(=\frac{5}{12}-\frac{7}{32}.\frac{6}{21}\)
\(=\frac{5}{12}-\frac{1}{16}\)
\(=\frac{\left(5.16\right)-\left(12.1\right)}{12.16}\)
\(=\frac{80-12}{192}\)
\(=\frac{68}{192}=\frac{17}{48}\)