Quy đồng mẫu số rồi so sánh hai phân số:
a) \(\dfrac{2}{5}\) và \(\dfrac{3}{10}\) b) \(\dfrac{7}{12}\) và \(\dfrac{5}{6}\) c) \(\dfrac{3}{4}\) và \(\dfrac{1}{2}\) d) \(\dfrac{8}{3}\) và \(\dfrac{11}{21}\)
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a) \(\dfrac{2}{3}=\dfrac{2.8}{3.8}=\dfrac{16}{24}\)
\(\dfrac{5}{8}=\dfrac{5.3}{8.3}=\dfrac{15}{24}\)
b) \(\dfrac{1}{4}=\dfrac{1.3}{4.3}=\dfrac{3}{12}\)
\(\dfrac{7}{12}=\dfrac{7.1}{12.1}=\dfrac{7}{12}\)
c) \(\dfrac{5}{6}=\dfrac{5.4}{6.4}=\dfrac{20}{24}\)
\(\dfrac{3}{8}=\dfrac{3.3}{8.3}=\dfrac{9}{24}\)
a) 23=2.83.8=162423=2.83.8=1624
58=5.38.3=152458=5.38.3=1524
b) 14=1.34.3=31214=1.34.3=312
712=7.112.1=712712=7.112.1=712
c) 56=5.46.4=202456=5.46.4=2024
38=3.38.3=924
a) \(\dfrac{3}{4}=\dfrac{3\times4}{4\times4}=\dfrac{12}{16}\)
b) \(\dfrac{1}{3}=\dfrac{1\times3}{3\times3}=\dfrac{3}{9}\)
c) \(\dfrac{5}{6}=\dfrac{5\times3}{6\times3}=\dfrac{15}{18}\)
a)\(\dfrac{3}{7}=\dfrac{3.8}{7.8}=\dfrac{24}{56};\dfrac{5}{8}=\dfrac{5.7}{8.7}=\dfrac{35}{56}\)
b)\(\dfrac{7}{10}=\dfrac{7.2}{10.2}=\dfrac{14}{20};\dfrac{3}{20}\)
c)\(\dfrac{9}{20}=\dfrac{9.9}{20.9}=\dfrac{81}{180};\dfrac{2}{9}=\dfrac{2.20}{9.20}=\dfrac{40}{180}\)
a) \(\dfrac{3}{4}=\dfrac{3\cdot5}{4\cdot5}=\dfrac{15}{20}\\ \dfrac{2}{5}=\dfrac{2\cdot4}{5\cdot4}=\dfrac{8}{20}\)
b) \(\dfrac{5}{12}=\dfrac{5\cdot3}{12\cdot3}=\dfrac{15}{36}\\ \dfrac{11}{36}=\dfrac{11}{36}\)
c) \(\dfrac{2}{3}=\dfrac{2\cdot4\cdot5}{3\cdot4\cdot5}=\dfrac{40}{60}\\ \dfrac{3}{4}=\dfrac{3\cdot3\cdot5}{4\cdot3\cdot5}=\dfrac{45}{60}\\ \dfrac{4}{5}=\dfrac{4\cdot3\cdot4}{5\cdot3\cdot4}=\dfrac{48}{60}\)
a) \(\dfrac{3}{4}\) và \(\dfrac{2}{5}\)
Mẫu số chung: 20
\(\dfrac{3}{4}=\dfrac{3.5}{4.5}=\dfrac{15}{20}\)
\(\dfrac{2}{5}=\dfrac{2.4}{5.4}=\dfrac{8}{20}\)
b) \(\dfrac{5}{12}\) và \(\dfrac{11}{36}\)
Mẫu số chung: 36
\(\dfrac{5}{12}=\dfrac{5.3}{12.3}=\dfrac{15}{36}\)
c) \(\dfrac{2}{3};\dfrac{3}{4}\) và \(\dfrac{4}{5}\)
Mẫu số chung: 60
\(\dfrac{2}{3}=\dfrac{2.20}{3.20}=\dfrac{40}{60}\\ \dfrac{3}{4}=\dfrac{3.15}{4.15}=\dfrac{45}{60}\\ \dfrac{4}{5}=\dfrac{4.12}{5.12}=\dfrac{48}{60}\)
a) \(< \)
b) \(>\)
c) \(< \)
d) \(>\)
e) \(< \)
g) \(>\)
h) \(>\)
k) \(>\)
a)
\(\dfrac{5}{9}< \dfrac{9}{9}\)
\(\dfrac{8}{7}>\dfrac{7}{7}\)
\(\dfrac{9}{9}=1\)
\(\dfrac{18}{4}>\dfrac{3}{4}\)
b)
\(\dfrac{2}{5},\dfrac{3}{5},\dfrac{8}{5}\)
\(\dfrac{5}{2}=\dfrac{15}{6},\dfrac{1}{6},1=\dfrac{6}{6}\rightarrow\dfrac{1}{6},\dfrac{6}{6},\dfrac{15}{6}\)
a) \(\dfrac{6}{14}=\dfrac{6:2}{14:2}=\dfrac{3}{7}\)
\(\dfrac{3}{7}< \dfrac{4}{7}\)
b) \(\dfrac{6}{15}=\dfrac{6:3}{15:3}=\dfrac{2}{5}\)
\(\dfrac{3}{5}>\dfrac{2}{5}\)
c) \(\dfrac{10}{18}=\dfrac{10:2}{18:2}=\dfrac{5}{9}\)
\(\dfrac{5}{9}>\dfrac{2}{9}\)
`3/7-2/5`
`=1/35>0`
`=>3/7>2/5`
`b,9>8`
`=>1/9<1/8`
`=>5/9<5/8`
`d,8/7>1`
`7/8<1`
`=>8/7>7/8`
a) \(\dfrac{2}{5}=\dfrac{4}{10}\)
\(\dfrac{4}{10}>\dfrac{3}{10}\)
b) \(\dfrac{5}{6}=\dfrac{10}{12}\)
\(\dfrac{7}{12}< \dfrac{10}{12}\)
c) \(\dfrac{1}{2}=\dfrac{2}{4}\)
\(\dfrac{3}{4}< \dfrac{2}{4}\)
d) \(\dfrac{8}{3}=\dfrac{56}{21}\)
\(\dfrac{56}{21}>\dfrac{11}{21}\)
\(\dfrac{3}{4}\) lớn hơn \(\dfrac{2}{4}\) à bạn