a: 34/56=17/28=1-11/28

42/53=1-11/53

mà 11/28>11/53

nên 34/56<42/53

b: 5/4=15/12; 7/6=14/12; 5/6=10/12

=>5/4>7/6>5/6

c: 4/3>1>99/100

a)      31/24

b)   5/6

c)     29/9 

bài 1

mik luoi lam

a) 

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

\(\Rightarrow\dfrac{1}{2}=\dfrac{1\times2}{2\times2}=\dfrac{2}{4}\)

Mà \(\dfrac{2}{4}< \dfrac{3}{4}\)

Vậy \(\dfrac{6}{12}< \dfrac{3}{4}\).

b)

\(\dfrac{8}{10}=\dfrac{8:2}{10:2}=\dfrac{4}{5}\)

Mà \(\dfrac{2}{5}< \dfrac{4}{5}\)

Vậy \(\dfrac{2}{5}< \dfrac{8}{10}\).

c)

\(\dfrac{40}{35}=\dfrac{40:5}{35:5}=\dfrac{8}{7}\)

Mà \(\dfrac{8}{7}>\dfrac{6}{7}\)

Vậy \(\dfrac{40}{35}>\dfrac{6}{7}\).

d)

\(\dfrac{8}{16}=\dfrac{8:8}{16:8}=\dfrac{1}{2}\)

Mà \(\dfrac{1}{2}< \dfrac{5}{2}\)

Vậy \(\dfrac{8}{16}< \dfrac{5}{2}\).

a) Ta có:

\(\dfrac{8}{9}=\dfrac{40}{45}\)

\(\dfrac{7}{5}=\dfrac{63}{45}\)

\(\Rightarrow\dfrac{8}{9}< \dfrac{6}{5}\left(\dfrac{40}{45}< \dfrac{63}{45}\right)\)

b) Ta có:

\(\dfrac{3}{4}=\dfrac{15}{20}\)

\(\dfrac{4}{5}=\dfrac{16}{20}\)

\(\Rightarrow\dfrac{3}{4}< \dfrac{4}{5}\left(\dfrac{15}{20}< \dfrac{16}{20}\right)\)

Câu `5`

`a)` Ta có:

`8/9 < 1 ; 7/5>1`

Vì: `8/9 < 1 < 7/5` nên `8/9 < 7/5`

`b)3/4= 15/20`

`4/5 = 16/20`

Vì: `15/20 < 16/20` nên `3/4<4/5`

Bài 2: 

a: 5/4<7/4

b: 2/3=34/51

9/17=27/51

mà 34>27

nên 2/3>9/17

Bài 3: 

a: 1/3+3/8=8/24+9/24=17/24

b: 7/6+5/18=21/18+5/18=26/18=13/9

Từng bài 1 thôi nhé

\(\dfrac{13}{17}< \dfrac{30}{34}\)                                        \(\dfrac{9}{8}>\dfrac{5}{7}\) 

 \(\dfrac{15}{7}< \dfrac{8}{3}\)                                        \(\dfrac{5}{7}< \dfrac{7}{5}\)                     

\(\dfrac{16}{20}=\dfrac{4}{5}\)

mình chưa học

a)\(\frac{3}{4}<\frac{4}{5}<\frac{5}{6}\)

b) \(\frac{3}{4}<\frac{5}{7}<\frac{7}{28}\)
 

C)\(\frac{5}{6}<\frac{7}{8}\)

d) \(\frac{7}{8}>\frac{5}{7}\)  
 

Tik chj nha

a)3/4<4/5<5/6

b)7/28<5/7<3/4

c)5/6<7/8

d)5/7<7/8