a)  =>  9, 7, 5, 2

b)   =>1, 4, 6, 8

a, 9; 7; 5; 2

b, 1; 6; 4; 8

câu a bạ sắp xếp rồi

mình chỉ làm câu b thôi

sắp xếp như sau:

\(\frac{7}{9};\frac{11}{9};\frac{43}{11};\frac{91}{89}\)

3/4,5/7,9/14

1/7;2/3;3/4;9/8;6/5

Ta có:
\(\dfrac{6}{5}=\dfrac{6\times168}{5\times168}=\dfrac{1008}{840}\)     ;    \(\dfrac{3}{4}=\dfrac{3\times210}{4\times210}=\dfrac{630}{840}\)     ;     \(\dfrac{9}{8}=\dfrac{9\times105}{8\times105}=\dfrac{945}{840}\) 

\(\dfrac{1}{7}=\dfrac{1\times120}{7\times120}=\dfrac{120}{840}\)     ;    \(\dfrac{2}{3}=\dfrac{2\times280}{3\times280}=\dfrac{560}{840}\)

⇒ \(\dfrac{120}{840}< \dfrac{560}{840}< \dfrac{630}{840}< \dfrac{945}{840}< \dfrac{1008}{840}\) ⇒ \(\dfrac{1}{7}< \dfrac{2}{3}< \)\(\dfrac{3}{4}< \dfrac{9}{8}< \dfrac{6}{5}\)
 

\(\frac{3}{2};\frac{4}{3};\frac{5}{4};\frac{6}{5};\frac{7}{6};\frac{8}{7};\frac{9}{8}\)

\(1\frac{1}{2};1\frac{1}{3};1\frac{1}{4};1\frac{1}{5};1\frac{1}{6};1\frac{1}{7};1\frac{1}{8}\)\(\frac{3}{2};\frac{4}{3};\frac{5}{4};\frac{6}{5};\frac{7}{6};\frac{8}{7};\frac{9}{8}\)

Vì \(\frac{1}{2}>\frac{1}{3}>\frac{1}{4}>\frac{1}{5}>\frac{1}{6}>\frac{1}{7}>\frac{1}{8}\)

=> \(1\frac{1}{2}>1\frac{1}{3}>1\frac{1}{4}>1\frac{1}{5}>1\frac{1}{6}>1\frac{1}{7}>1\frac{1}{8}\)

Hay    \(\frac{3}{2}>\frac{4}{3}>\frac{5}{4}>\frac{6}{5}>\frac{7}{6}>\frac{8}{7}>\frac{9}{8}\)

\(\frac{3}{2};\frac{4}{3};\frac{5}{4};\frac{6}{5};\frac{7}{6};\frac{8}{7};\frac{9}{8}\)

\(\frac{3}{2};\frac{4}{3};\frac{5}{4};\frac{6}{5};\frac{7}{6};\frac{8}{7};\frac{9}{8}\)\(\frac{3}{2};\frac{4}{3};\frac{5}{4};\frac{6}{5};\frac{7}{6};\frac{8}{7};\frac{9}{8}\)

9/8,8/7,7/6,6/5,5/4,4/2,3/2

4/9 ; 8/9 ; 5/4 ; 4/3 ; 5/3

\(\dfrac{4}{9};\dfrac{8}{9};\dfrac{5}{4};\dfrac{4}{3};\dfrac{5}{3}\)

a: -10/8<-1

-19/19=-1

-1<-2/10<0

0<5/12<1<17/15

=>17/15>1>5/12>-2/10>-19/19>-10/8

b: -1/3=-4/12; -5/12=-5/12; -3/4=-9/12; -1/4=-3/12; -7/12=-7/12

=>-3/4<-7/12<-5/12<-1/3<-1/4

Theo thứ tự từ lớn đến bé:\(\dfrac{17}{15};1;\dfrac{5}{12};0;\dfrac{2}{-10};-\dfrac{19}{19};-\dfrac{10}{8}\)

Theo thứ tự từ bé đến lớn : \(-\dfrac{3}{4};-\dfrac{7}{12};-\dfrac{5}{12};-\dfrac{1}{3};\dfrac{1}{-4}\)

\(\dfrac{1}{2}< \dfrac{1+1}{2+1}=\dfrac{2}{3}\)

\(\dfrac{2}{3}< \dfrac{2+1}{3+1}=\dfrac{3}{4}\)

\(\dfrac{3}{4}< \dfrac{3+1}{4+1}=\dfrac{4}{5}\)

\(\dfrac{4}{5}< \dfrac{4+1}{5+1}=\dfrac{5}{6}\)

\(\dfrac{5}{6}< \dfrac{5+1}{6+1}=\dfrac{6}{7}\)

\(\)Vậy \(\dfrac{1}{2}< \dfrac{2}{3}< \dfrac{3}{4}< \dfrac{4}{5}< \dfrac{5}{6}< \dfrac{6}{7}\)

71,62,56,44,25,7,3,1

Ta có : \(\dfrac{4}{5}< 1\) ; \(\dfrac{4}{7}< 1\) \((\) vì có cùng tử số mà mẫu số lớn hơn thì bé hơn \()\)

\(\dfrac{2}{1}=2;\dfrac{6}{2}=3;\dfrac{9}{8}>1;\dfrac{8}{5}>1\)

\(\Rightarrow\) thứ tự từ bé đến lớn:\(\dfrac{4}{7};\dfrac{4}{5};\dfrac{9}{8};\dfrac{8}{5};\dfrac{2}{1};\dfrac{6}{2}\)

\(#Vy\)