a: \(-\dfrac{49}{211}< 0\)
\(0< \dfrac{13}{1999}\)
Do đó: \(-\dfrac{49}{211}< \dfrac{13}{1999}\)
b: \(\dfrac{311}{256}>1\)
\(1>\dfrac{199}{203}\)
Do đó: \(\dfrac{311}{256}>\dfrac{199}{203}\)
c: \(\dfrac{99}{-98}< 0\)
\(0< \dfrac{33}{49}\)
Do đó: \(\dfrac{99}{-98}< \dfrac{33}{49}\)
d: \(\dfrac{105}{106}< 1\)
\(1< \dfrac{94}{93}\)
Do đó: \(\dfrac{105}{106}< \dfrac{94}{93}\)