a.-3/4 < 2/4

b.-8/13 > -12/13

c.-3/7 < 4/5

d.12/-18 = -2/3 

a)4/9<13/18

b)-15/7<-6/5

a) Ta có: 4/9 = 4 . 2 / 9 . 2 = 8/18

Vì 8/18 < 13/18 nên 4/9 < 13/18.

b) Ta có: -15/7 = -15 . 5 / 7 . 5 = -75/35; -6/5 = -6 . 7 / 5 . 7 = -42/35

Vì -75/35 < -42/35 nên -15/7 < -6/5.

a) \(\frac{4}{9}=\frac{4.2}{9.2}=\frac{8}{18}\)

MÀ \(\frac{8}{18}< \frac{13}{18}\) 

\(\Rightarrow\frac{4}{9}< \frac{13}{18}\)

b) \(\frac{-15}{7}=\frac{-15.5}{7.5}=\frac{-75}{35}\)

\(\frac{-6}{5}=\frac{-6.7}{5.7}=\frac{-42}{35}\)

Vì -75 < -42

=> \(\frac{-75}{35}< \frac{-42}{35}\)

\(\Rightarrow\frac{-15}{7}< \frac{-6}{5}\)

mình chưa học

Co j góc lệch cùng trời cuối đất cú mèo

Bài 1: 

a) \(\dfrac{-5}{6}\ne\dfrac{10}{-14}\left(\dfrac{10}{-14}=-\dfrac{5}{7}\right).\)

b) \(\dfrac{-15}{-60}\ne\dfrac{-3}{12}\left(\dfrac{-15}{-60}=\dfrac{1}{4}\right).\)

Bài 2:

a) \(\dfrac{20}{-140}=-\dfrac{1}{7}.\)

b) \(\dfrac{4.18}{9.12}=\dfrac{72}{108}=\dfrac{2}{3}.\)

c) \(\dfrac{17.25-17.3}{2.\left(-15\right)}=\dfrac{17.\left(25-3\right)}{-30}=-\dfrac{17.22}{30}=\dfrac{374}{30}=\dfrac{187}{15}.\)

Bài 3:

a) \(\dfrac{-3}{5}< \dfrac{4}{-7}.\)

b) \(\dfrac{-4}{21}>\dfrac{-7}{35}.\)

c) \(\dfrac{-7}{24}>\dfrac{-2}{3}.\)

d) \(\dfrac{-52}{167}< \dfrac{-3}{-4}.\)

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

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

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