`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

ta có: 3215/3216 <1

3104/3103>1

suy ra: 3215/3216 < 3104/3103

\(\frac{3}{-7}\)= \(\frac{3x8}{-7x8}\)=\(\frac{24}{-56}\)

\(\frac{5}{8}\)=\(\frac{5x-7}{8x-7}\)=\(\frac{-35}{-56}\)

Vậy quy đồng mẫu số \(\frac{3}{-7}\)và \(\frac{5}{8}\)là : \(\frac{24}{-56}\)và \(\frac{-36}{-56}\)

Nếu so sánh thì ta thấy :\(\frac{24}{-56}\)>\(\frac{-36}{-56}\)

27/81=1/3

57/76=3/4

35/84=5/12

27/81=1/3

57/76=3/4

35/84=5/12

567895464468457899999 hư đi em 

27/81=3/9=1/3

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

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

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

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

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

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

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

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

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

Quy tắc:

Trong hai phân số có cùng mẫu, phân số nào có tử lớn hơn thì lớn hơn.

So sánh:

Ta có 7 < 9 nên \(\dfrac{7}{{11}} < \dfrac{9}{{11}}\).