Ta có:

\(\frac{-181818}{313131}=\frac{-181818:10101}{313131:10101}=\frac{-18}{31}\)

Vì \(\frac{-18}{31}=\frac{-18}{31}\)

\(\Rightarrow\frac{-18}{31}=\frac{-181818}{313131}\)

181818/313131=18/31

suy ra -18/31 < 181818/313131

Ta có : \(\frac{-18}{31}\) và   \(\frac{-181818}{313131}=\frac{\left(-181818\right):10101}{313131:10101}=\frac{-18}{31}\)

Vì \(\frac{-18}{31}=\frac{-18}{31}\)nên \(\frac{-18}{31}=\frac{-181818}{313131}\)

Vậy  \(\frac{-18}{31}=\frac{-181818}{313131}\)

Ta co :\(-\frac{18}{13}\&-\frac{181818}{313131}\)

\(\Rightarrow\frac{-181818}{313131}=-\frac{18}{31}\)

Vi :\(-\frac{18}{31}=-\frac{18}{31}\)

vay :\(-\frac{18}{31}=-\frac{181818}{313131}\)

-181818/313131=-18/31

vi-18/31=-18/31nen -18/31=-181818/313131

\(\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)

\(\frac{27}{31}=\frac{27.101}{31.101}=\frac{27.10101}{31.10101}\)

\(\frac{27}{31}=\frac{27}{31}=\frac{27}{31}\)

\(\Rightarrow\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)

\(\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)

\(\frac{27}{31}=\frac{27\cdot101}{31\cdot101}=\frac{27\cdot10101}{31\cdot10101}\)

\(\Rightarrow\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)

-18/31 và -181818/313131

-181818/313131= -181818:18/-313131:31=-18/31

=> -18/31 = -181818/-313131

\(-\frac{18}{31}=-\frac{18}{31}\)

\(-\frac{181818}{313131}=-\frac{18.10101}{31.10101}=-\frac{18}{31}\)

Do  \(-\frac{18}{31}=-\frac{18}{31}\)

\(\Rightarrow-\frac{18}{31}=-\frac{181818}{313131}\)

ta có:

\(\frac{-181818}{313131}=\frac{-181818\div10101}{313131\div10101}=\frac{-18}{31}\)

Vậy \(\frac{-18}{31}=\frac{-181818}{313131}\)

So sánh : 

-19/31 và -191919/313131

-191919/313131= -19/31

Vì -19/31 = -19/31

=> -19/31 = -191919/313131

Vậy -19/31 = -191919/313131 

Ta có : \(\frac{151515}{-313131}=\frac{151515:10101}{-313131:10101}=\frac{15}{-31}=-\frac{15}{31}\)

Vậy \(-\frac{15}{31}=\frac{151515}{-313131}\)