a) -23/49 = -1081/2303

   -25/47 = -1225/2303

=> -1081/2303 > -1225/2303 hay -23/49 > -25/47

b) -317/633 = -235531/470319

   -371/743 = -234843/470319

=> -235531/470319 < -234843/470319 hay -317/633 < -371/743

a) Ta có \(\dfrac{23}{27}>\dfrac{23}{29};\dfrac{23}{29}>\dfrac{22}{29}\)

Vậy \(\dfrac{23}{27}>\dfrac{22}{29}\)

b) Ta có \(\dfrac{15}{25}=1-\dfrac{2}{5}\)

\(\dfrac{25}{49}=1-\dfrac{24}{49}\)

Vì \(\dfrac{2}{5}=\dfrac{24}{60}< \dfrac{24}{49}\)

Vậy \(\dfrac{15}{25}>\dfrac{25}{49}\)

23/27 lớn hơn 22/29

15/25 lớn hơn 25/49

a, Ta có: \(-\dfrac{317}{633}< -\dfrac{1}{2}\left(1\right)\)

\(\dfrac{-371}{743}>-\dfrac{1}{2}\left(2\right)\)

Từ (1); (2), Suy ra:

\(-\dfrac{317}{633}< \dfrac{-371}{743}\)

b, Ta có: \(\dfrac{-24}{35}< \dfrac{-24}{36}=\dfrac{-2}{3}\left(1\right)\)

\(\dfrac{-19}{30}>\dfrac{-20}{30}=\dfrac{-2}{3}\left(2\right)\)

Từ (1); (2) Suy ra:

\(\dfrac{-24}{35}< \dfrac{-19}{30}\)

a)=

b)>

c)=

a) \(\dfrac{21}{23}>\dfrac{19}{23}\)

\(\dfrac{8}{5}=\dfrac{49}{30}\)

\(\dfrac{23}{36}>\dfrac{5}{9}\)

b) \(\dfrac{11}{15}>\dfrac{11}{17}\)

\(\dfrac{26}{13}=2\)

\(3< \dfrac{16}{5}\)

c) \(\dfrac{8}{9}< 1\)

\(1< \dfrac{31}{27}\)

\(\dfrac{8}{9}< \dfrac{31}{27}\)

a,

Ta có:
\(\dfrac{3}{7}=1-\dfrac{4}{7}\)
\(\dfrac{11}{15}=1-\dfrac{4}{15}\)
So sánh phân số \(\dfrac{4}{7}\) và \(\dfrac{4}{15}\)
Vì \(7< 15\) nên \(\dfrac{1}{7}>\dfrac{1}{15}\)
\(\Rightarrow1-\dfrac{4}{7}< 1-\dfrac{4}{15}\)
Vậy \(\dfrac{3}{7}< \dfrac{11}{15}\)

b)

\(\dfrac{-11}{6}< -1< \dfrac{-8}{9}\) nên \(\dfrac{-11}{6}< \dfrac{-8}{9}\)

c) 

\(\dfrac{305}{25}=\dfrac{305:5}{25:5}=\dfrac{61}{5}\)
Ta có: 
Mẫu số chung 2 phân số: 80
\(\dfrac{297}{16}=\dfrac{297*5}{16*5}=\dfrac{1485}{80}\)
\(\dfrac{61}{5}=\dfrac{61*16}{5*16}=\dfrac{976}{80}\)
Vì \(1485>976\) nên\(\dfrac{1485}{80}>\dfrac{976}{80}\)
Vậy \(\dfrac{297}{16}>\dfrac{305}{25}\)

d,

$\frac{-205}{317}=\frac{-205:-1}{317:-1}=\frac{205}{-317}$
Ta có: 
Mẫu số chung 2 phân số: -35187
\(\dfrac{205}{-317}=\dfrac{205*111}{-317*111}=\dfrac{22755}{-35187}\)
\(\dfrac{-83}{111}=\dfrac{-83*-317}{111*-317}=\dfrac{26311}{-35187}\)
Vì \(22755< 26311\) nên\(\dfrac{22755}{-35187}< \dfrac{26311}{-35187}\)
Vậy \(\dfrac{-205}{317}< \dfrac{-83}{111}\)

Câu d, mình làm sai, cho mình sửa lại:

\(\dfrac{-205}{317}=\dfrac{-22755}{35187}\)

\(\dfrac{-83}{111}=\dfrac{-26311}{35187}\)

Vậy là  \(-22755>-26311\) hay \(\dfrac{-205}{317}>\dfrac{-83}{111}\)

Câu 1:

a) \(\dfrac{-15}{17}\) và \(\dfrac{-19}{21}\)

Ta có: \(\dfrac{-15}{17}=-1+\dfrac{2}{17}\); \(\dfrac{-19}{21}=-1+\dfrac{2}{21}\)

Vì \(\dfrac{2}{17}>\dfrac{2}{21}\)

Do đó: \(\dfrac{-15}{17}>\dfrac{19}{-23}\)

b) \(\dfrac{-13}{19}\) và \(\dfrac{19}{-23}\)

Ta có: \(\dfrac{19}{23}>\dfrac{19}{25}\); \(\dfrac{13}{19}=1-\dfrac{6}{19}\); \(\dfrac{19}{25}=1-\dfrac{6}{25}\)

mà \(\dfrac{6}{19}>\dfrac{6}{25}\) \(\Rightarrow\dfrac{13}{19}< \dfrac{19}{25}< \dfrac{19}{23}\)

Vì \(\dfrac{13}{19}< \dfrac{19}{23}\Rightarrow\dfrac{-13}{19}>\dfrac{19}{-23}\)

c) \(\dfrac{-24}{35}\) và \(\dfrac{-19}{30}\)

Ta có: \(\dfrac{-24}{35}=-1+\dfrac{19}{35}\);\(\dfrac{-19}{30}=-1+\dfrac{11}{30}\)

Vì \(\dfrac{11}{35}< \dfrac{11}{30}\)

Do đó: \(\dfrac{-24}{35}< \dfrac{-19}{30}\)

d) \(\dfrac{-1941}{1931}\) và \(\dfrac{-2011}{2001}\); \(\dfrac{-2011}{2001}=-1+\dfrac{10}{2001}\)

Vì \(\dfrac{10}{1931}< \dfrac{10}{1001}\)

Do đó: \(\dfrac{-1941}{1931}< \dfrac{-2011}{2001}\)

Ta có: \(\dfrac{-1941}{1931}=-1+\dfrac{10}{1931}\)