Question

bài 3: rút gọn rồi tính: 30/24 : 5/6 ; 28/42 : 4/5 ; 7/12 : 21/18 ; 50/84 : 5/7

Answer 1

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Answer 2

\(\dfrac{30}{24}:\dfrac{5}{6}=\dfrac{5}{4}:\dfrac{5}{6}=\dfrac{5}{4}\times\dfrac{6}{5}=\dfrac{6}{4}=\dfrac{3}{2}\)

\(\dfrac{28}{42}:\dfrac{4}{5}=\dfrac{2}{3}\times\dfrac{5}{4}=\dfrac{10}{12}=\dfrac{5}{6}\)

\(\dfrac{7}{12}:\dfrac{21}{18}=\dfrac{7}{12}:\dfrac{7}{6}=\dfrac{6}{12}=\dfrac{1}{2}\)

\(\dfrac{50}{84}:\dfrac{5}{7}=\dfrac{25}{42}\times\dfrac{7}{5}=\dfrac{1}{5\times6}=\dfrac{1}{30}\)

Answer 3

`30/24 : 5/6 = 5/4 : 5/6  = 5/4 xx 5/6 = 3/2`

`28/42 : 4/5 = 2/3 : 4/5 = 2/3 xx 5/4 = 5/6`

`7/12 : 21/18 = 7/12 : 7/6 = 7/12 xx 6/7 = 1/2`

`50/84 : 5/7 = 25/42 : 5/7= 25/42 xx 7/5 = 1/30`