Question

1) so xánh các số hửu tỉ một cách nhanh nhất :

a) -1,6 và  \(-\dfrac{7}{4}\)   b) \(\dfrac{2018}{2019}\) và \(\dfrac{2019}{2020}\)

c) \(\dfrac{-1234}{1244}\) và \(\dfrac{-4321}{4331}\)

Answer 1

a: \(-\dfrac{7}{4}=-1,75< -1,6\)

b: \(\dfrac{2018}{2019}=1-\dfrac{1}{2019};\dfrac{2019}{2020}=1-\dfrac{1}{2020}\)

2019<2020

=>\(\dfrac{1}{2019}>\dfrac{1}{2020}\)

=>\(-\dfrac{1}{2019}< -\dfrac{1}{2020}\)

=>\(-\dfrac{1}{2019}+1< -\dfrac{1}{2020}+1\)

=>\(\dfrac{2018}{2019}< \dfrac{2019}{2020}\)

c: \(\dfrac{-1234}{1244}=-1+\dfrac{10}{1244};\dfrac{-4321}{4331}=-1+\dfrac{10}{4331}\)

mà \(\dfrac{10}{1244}>\dfrac{10}{4331}\)

nên \(-\dfrac{1234}{1244}>\dfrac{-4321}{4331}\)