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`4/7+4`
`=4/7+4/1`
`=4/7+28/7`
`=32/7`
__
`3+6/11`
`=33/11+6/11`
`=39/11`
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`3-5/7`
`=3/1-5/7`
`=21/7-5/7`
`=16/7`
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`21/9-2`
`=21/9-18/9`
`=3/9`
`=1/3`
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`15/24+2`
`=15/24+48/24`
`=63/24`
`=21/16`
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`63/45-20/25`
`=63/45-4/5`
`=63/45-36/45`
`=27/45`
`=9/15`
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`3/4-2/8`
`=3/4-1/4`
`=2/4`
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`6/7-5/8`
`=48/56-35/56`
`=13/56`
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`37/45-5/9`
`=37/45-25/45`
`=12/45`
`=4/15`
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`46/39-11/13`
`=46/39-33/39`
`=13/39`
`=1/2`
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`5/12+3/4+1/3`
`=5/12+9/12+4/12`
`=14/12+4/12`
`=18/12`
`=3/2`
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`1/2+3/7+11/14`
`=7/14+6/14+11/14`
`=13/14+11/14`
`=24/14`
`=12/7`
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`7/10-(1/5+1/4)`
`=7/10-(4/20+5/20)`
`=7/10-9/20`
`=14/20-9/20`
`=5/20`
`=1/4`
__
`15/4-2/3-3/4`
`=(15/4-3/4)-2/3`
`=12/4-2/3`
`=3-2/3`
`=9/3-2/3`
`=7/3`
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5}{8}+\dfrac{7}{24}\) = \(\dfrac{15}{24}\) + \(\dfrac{7}{24}\) = \(\dfrac{22}{24}\) = \(\dfrac{11}{12}\)
\(\dfrac{6}{5}+\dfrac{9}{30}=\dfrac{36}{30}+\dfrac{9}{30}=\dfrac{45}{30}=\dfrac{3}{2}\)
\(\dfrac{7}{12}\) + \(\dfrac{5}{2}\) = \(\dfrac{7}{12}+\dfrac{30}{12}=\dfrac{37}{12}\)
\(\dfrac{9}{21}\) + \(\dfrac{6}{49}\) = \(\dfrac{3}{7}\) + \(\dfrac{6}{49}\) = \(\dfrac{21}{49}\) + \(\dfrac{6}{49}\) = \(\dfrac{27}{49}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a.\(\dfrac{27}{8}\)
b.\(\dfrac{37}{40}\)
c.\(\dfrac{5}{2}\)
d.\(\dfrac{7}{3}\)
e.5
g.\(\dfrac{53}{16}\)
Bài 1 :
a) \(\dfrac{3}{2}+\dfrac{5}{4}+\dfrac{5}{8}=\dfrac{12}{8}+\dfrac{10}{8}+\dfrac{5}{8}=\dfrac{12+10+5}{8}=\dfrac{27}{8}\)
b) \(\dfrac{4}{5}-\dfrac{3}{8}+\dfrac{2}{4}=\dfrac{32}{40}-\dfrac{15}{40}+\dfrac{20}{40}=\dfrac{32-15+20}{40}=\dfrac{37}{40}\)
c) \(3+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{3}{1}+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{24}{8}+\dfrac{6}{8}-\dfrac{10}{8}=\dfrac{20}{8}=\dfrac{5}{2}\)
d) \(\dfrac{5}{6}-\dfrac{1}{2}+2=\dfrac{5}{6}-\dfrac{1}{2}+\dfrac{2}{1}=\dfrac{5}{6}-\dfrac{3}{6}+\dfrac{12}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)
e) \(\dfrac{3}{5}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{2}{5}+\dfrac{16}{11}+\dfrac{19}{13}=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)=1+2+2=5\)
g) \(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}=\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{13}{32}=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{29}{32}+\dfrac{13}{32}\right)=1+1+\dfrac{21}{16}=2+\dfrac{21}{16}=\dfrac{53}{16}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
`3/7 + 4/5 + 4/7`
`= (3/7 +4/7)+4/5`
`= 7/7 +4/5`
`= 1 + 4/5`
`= 5/5 +4/5`
`=9/5`
`------`
`6/11 + 2/15 + 5/11`
`=(6/11 + 5/11)+2/15`
`= 1 + 2/15`
`= 15/15 +2/15`
`= 17/15`
`-----`
`4/9 + 2/5 + 15/27`
`= (4/9 + 15/27 )+2/5`
`= 1+2/5`
`=5/5 +2/5`
`=7/5`
`-----`
`6/13 + 9/32 + 21/26`
`= (6/13 + 21/26)+9/32`
`= ( 12/26 + 21/26)+9/32`
`= 33/26 +9/32`
`=645/416`
![](https://rs.olm.vn/images/avt/0.png?1311)
a: 7/8<8/9<9/10<10/11<11/12
b: 4/5<5/6<6/7<7/8
c: 1/3<3/5<7/9<9/11<11/13
\(\frac{7}{9}+\frac{6}{7}\times\frac{4}{5}=\frac{7}{9}+\frac{24}{35}=\frac{361}{315}\)
\(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{16}{15}=\frac{548}{345}\)
\(\frac{5}{8}\times\frac{4}{9}:\frac{2}{3}=\frac{5}{18}:\frac{2}{3}=\frac{5}{12}\)
\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{11}{24}\)
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,
\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{13}{24}\)
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