\(a.\dfrac{2}{-9}và\dfrac{8}{-9}\)
Ta có: \(\dfrac{-2}{9}và\dfrac{-8}{9}\)
vì -2 > -8
-> \(\dfrac{2}{-9}>\dfrac{8}{-9}\)
\(b.\dfrac{-2}{5}và\dfrac{-3}{4}\)
Ta có: \(\dfrac{-2}{5}=\dfrac{-8}{20};\dfrac{-3}{4}=\dfrac{-15}{20}\)
Vì -8 > -15
=> \(\dfrac{-2}{5}>\dfrac{-3}{4}\)