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

Cô làm rồi em nhé:

https://olm.vn/cau-hoi/giup-em-voiii.8161766187032

Câu 1 : 

\(\dfrac{-25}{37}\&\dfrac{-20}{31}\)

Ta thấy \(\dfrac{-25}{37}< \dfrac{-20}{37}\)

mà \(\dfrac{-20}{37}< \dfrac{-20}{31}\)

\(\Rightarrow\dfrac{-25}{37}< \dfrac{-20}{31}\)

Câu 2 :

\(\dfrac{2}{3}\&\dfrac{5}{7}\)

\(\dfrac{2}{3}:\dfrac{5}{7}=\dfrac{2}{3}.\dfrac{7}{5}=\dfrac{14}{15}< 1\)

Ta thấy \(\dfrac{8}{13}:\dfrac{5}{7}=\dfrac{8}{13}.\dfrac{7}{5}=\dfrac{56}{65}< 1\)

a) \(\frac{-2}{3}>\frac{4}{-5}\)
b) \(\frac{-18}{31}< \frac{-18.18.18}{31.31.31}\)
c) \(\frac{-13}{31}< \frac{29}{-88}\)

bạn nào làm cụ thể hơn thì mình k nhaa ! camon mng

97/98 < 2018/2019

-25/26 < -18/31

-9/11 > -13/12

a: \(x_1=x_2=x_3=x_4\)