a) Ta có: 4/9 = 4 . 2 / 9 . 2 = 8/18
Vì 8/18 < 13/18 nên 4/9 < 13/18.
b) Ta có: -15/7 = -15 . 5 / 7 . 5 = -75/35; -6/5 = -6 . 7 / 5 . 7 = -42/35
Vì -75/35 < -42/35 nên -15/7 < -6/5.
a) \(\frac{4}{9}=\frac{4.2}{9.2}=\frac{8}{18}\)
MÀ \(\frac{8}{18}< \frac{13}{18}\)
\(\Rightarrow\frac{4}{9}< \frac{13}{18}\)
b) \(\frac{-15}{7}=\frac{-15.5}{7.5}=\frac{-75}{35}\)
\(\frac{-6}{5}=\frac{-6.7}{5.7}=\frac{-42}{35}\)
Vì -75 < -42
=> \(\frac{-75}{35}< \frac{-42}{35}\)
\(\Rightarrow\frac{-15}{7}< \frac{-6}{5}\)