a: \(\dfrac{1234}{1235}=1-\dfrac{1}{1235};\dfrac{4319}{4320}=1-\dfrac{1}{4320}\)
1235<4320
=>\(\dfrac{1}{1235}>\dfrac{1}{4320}\)
=>\(-\dfrac{1}{1235}< -\dfrac{1}{4320}\)
=>\(-\dfrac{1}{1235}+1< -\dfrac{1}{4320}+1\)
=>\(\dfrac{1234}{1235}< \dfrac{4319}{4320}\)
b: \(\dfrac{-1234}{1244}=-1+\dfrac{10}{1244};\dfrac{-4321}{4331}=-1+\dfrac{10}{4331}\)
mà \(\dfrac{10}{1244}>\dfrac{10}{4331}\)
nên \(-\dfrac{1234}{1244}>\dfrac{-4321}{4331}\)
c: \(\dfrac{-31}{-32}=\dfrac{31}{32}=\dfrac{31\cdot32327}{32\cdot32327}=\dfrac{1002137}{1034464};\dfrac{31317}{32327}=\dfrac{31317\cdot32}{32327\cdot32}=\dfrac{1002144}{1034464}\)
mà 1002137<1002144
nên \(\dfrac{-31}{-32}< \dfrac{31317}{32327}\)
d: \(\dfrac{3246}{-3247}=\dfrac{-3246}{3247}>-1;-1=\dfrac{-45983}{45983}>\dfrac{-45984}{45983}\)
Do đó: \(\dfrac{3246}{-3247}>\dfrac{-45984}{45983}\)
e: \(\dfrac{22}{67}< \dfrac{22}{66}=\dfrac{1}{3};\dfrac{51}{152}>\dfrac{51}{153}=\dfrac{1}{3}\)
Do đó: \(\dfrac{22}{67}< \dfrac{51}{152}\)
=>\(\dfrac{22}{-67}>\dfrac{51}{-152}\)
f: \(\dfrac{-18}{91}< -\dfrac{18}{90}=-\dfrac{1}{5}\)
\(\dfrac{-1}{5}=\dfrac{-23}{115}< -\dfrac{23}{114}\)
Do đó: \(-\dfrac{18}{91}< -\dfrac{23}{114}\)
