27/81=3/9=1/3

có lộn đề ko vậy trời ????????????????????????????????????????

`27/81=(27:27)/(81:27)=1/3`

`57/76=(57:19)/(76:19)=3/4`

`35/84=(35:7)/(84:7)=5/12`

`MSC:12`

`1/3=(1xx4)/(3xx4)=4/12`

`3/4=(3xx3)/(4xx3)=9/12`

`5/12` giữ nguyên

\(\dfrac{27}{81}=\dfrac{1}{3}\); \(\dfrac{57}{76}=\dfrac{3}{4}\); \(\dfrac{35}{84}=\dfrac{5}{12}\)

\(\dfrac{1}{3}=\dfrac{4}{12}\)

\(\dfrac{3}{4}=\dfrac{9}{12}\)

Giữa nguyên 5/12

\(a.\dfrac{5}{10}=\dfrac{1}{2}=\dfrac{1\times3}{2\times3}=\dfrac{3}{6}\)

\(\dfrac{25}{75}=\dfrac{1}{3}=\dfrac{1\times2}{3\times2}=\dfrac{2}{6}\)

\(b.\dfrac{42}{56}=\dfrac{3}{4}=\dfrac{3\times2}{4\times2}=\dfrac{6}{8}\)

\(\dfrac{18}{48}=\dfrac{3}{8}\)

\(c.\dfrac{27}{81}=\dfrac{1}{3}=\dfrac{1\times4}{3\times4}=\dfrac{4}{12}\)

\(\dfrac{57}{76}=\dfrac{3}{4}=\dfrac{3\times3}{4\times3}=\dfrac{9}{12}\)

\(\dfrac{35}{84}=\dfrac{5}{12}\)

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a.3/6 va 2/6     b.24/32 va12/32  c.912/2736  2052/2736 1140/2736 

− 51 136 = − 3 8 ; − 60 108 = − 5 9 ; 26 − 156 = − 1 6

− 3 8 = − 27 72 ; − 5 9 = − 40 72 ; − 1 6 = − 12 72

− 165 270 = 11 18 ; − 91 156 = − 7 12 ; − 210 1134 = 5 27

11 18 = 66 108 ; − 7 12 = − 63 108 ; 5 27 = 20 108