21/15=21:3/15:3=7/5

11/121=11:11/121:11=1/11

27/72=27:9/72:9=3/8

\(\dfrac{21}{15}=\dfrac{7}{5};\dfrac{11}{121}=\dfrac{1}{11};\dfrac{27}{72}=\dfrac{3}{8}\)

\(\dfrac{21}{15}=\dfrac{21:3}{15:3}=\dfrac{7}{5}\)

\(\dfrac{11}{121}=\dfrac{11:11}{121:11}=\dfrac{1}{11}\)

\(\dfrac{27}{72}=\dfrac{27:9}{72:9}=\dfrac{3}{8}\)

21/15=7/5

11/121=1/11

27/72=3/8

a) >

b) =

c) >

d) <

2/3>3/7

2/5=2/5

11/7>11/8

52/91<5/7

a ) >

b ) =

c)>

d)<

giúp mình đi mà

80/24=10/3

a)\(\dfrac{56}{70}=\dfrac{56:14}{70:14}=\dfrac{4}{5}\)

b)\(\dfrac{-120}{86}=\dfrac{-120:2}{86:2}=-\dfrac{60}{43}\)

c)\(\dfrac{915+85}{1017-117}=\dfrac{1000}{900}=\dfrac{10}{9}\)

d)\(\dfrac{3838}{5454}=\dfrac{19}{27}\)

a) \(\dfrac{56}{70}=\dfrac{4}{5}\)

\(b,-\dfrac{120}{86}=-\dfrac{60}{43}\)

\(c,\dfrac{10}{9}\)

\(d,\dfrac{19}{27}\)

ta có : 52/91=4/7

60/84=5/7

Vì mẫu 2 phân số trên bằng nhau, 4<5 nên 4/7<5/7

hay 52/91<60/84

Vậy  ....

52/91=4/7(1)

60/84=4/7(2)

Từ (1) và (2) => 52/91=60/84

Chào bạn, bạn theo dõi bài giải của mình nhé! 

Ta có : 

\(\frac{52}{91}=\frac{52:13}{91:13}=\frac{4}{7}\)

\(\frac{60}{84}=\frac{60:12}{84:12}=\frac{5}{7}\)

Ta có : \(\frac{4}{7}<\frac{5}{7}\left(vì:4<5\right)\)

Chúc bạn học tốt!

-18

-18

-90/5= -18

\(\dfrac{3.\left(-5\right)}{15.\left(-6\right)}=\dfrac{3.\left(-5\right)}{\left(-5\right)\left(-3\right)\left(-6\right)}=\dfrac{-1}{-6}=\dfrac{1}{6}\)