Question

So sánh các số hữu tỉ sau bằng cách nhanh nhất :

a) \(-\dfrac{1}{5}\) và \(\dfrac{1}{1000}\)

b) \(\dfrac{267}{-268}\) và \(-\dfrac{1347}{1343}\)

c) \(-\dfrac{13}{38}\) và \(\dfrac{29}{-88}\)

d) \(-\dfrac{18}{31}\) và \(-\dfrac{181818}{313131}\)

Answer 1

a) Ta có : \(\dfrac{-1}{5}< 0< \dfrac{1}{1000}\)

\(\Rightarrow\dfrac{-1}{5}< \dfrac{1}{1000}\)

b) Ta có : \(\dfrac{267}{268}< 1< \dfrac{1347}{1343}\)

=> \(\dfrac{267}{-268}< -\dfrac{1347}{1343}\)

c) \(\dfrac{13}{38}>\dfrac{13}{39}=\dfrac{1}{3}=\dfrac{19}{87}>\dfrac{29}{88}\)

=> \(-\dfrac{13}{38}< \dfrac{29}{-88}\)

d) \(\dfrac{181818}{313131}=\dfrac{18}{31}\)

=> \(-\dfrac{18}{31}=-\dfrac{181818}{313131}\)