Đáp án:
a)
$\dfrac{-25}{19}<\dfrac{-13}{19}<\dfrac{9}{19}<\dfrac{14}{19}<\dfrac{20}{19}<\dfrac{30}{19}<\dfrac{42}{19}$
b)
$\dfrac{-2}{15}<\dfrac{-1}{10}<\dfrac{1}{6}<\dfrac{1}{5}<\dfrac{4}{15}<\dfrac{1}{3}<\dfrac{-2}{-5}$
Giải thích các bước giải:
a)
vì $-25<-13<9<14<20<30<42$
Nên $\dfrac{-25}{19}<\dfrac{-13}{19}<\dfrac{9}{19}<\dfrac{14}{19}<\dfrac{20}{19}<\dfrac{30}{19}<\dfrac{42}{19}$
b)
$\dfrac{1}{3}=\dfrac{10}{30}\\
\dfrac{1}{5}=\dfrac{6}{30}\\
\dfrac{-2}{15}=\dfrac{-4}{30}\\
\dfrac{1}{6}=\dfrac{5}{30}\\
\dfrac{-2}{-5}=\dfrac{12}{30}\\
\dfrac{-1}{10}=\dfrac{-3}{30}\\
\dfrac{4}{15}=\dfrac{8}{30}$
Vì $-4<-3<5<6<8<10<12$
Nên $\dfrac{-4}{30}<\dfrac{-3}{30}<\dfrac{5}{30}<\dfrac{6}{30}<\dfrac{8}{30}<\dfrac{10}{30}<\dfrac{12}{30}$
Vậy $\dfrac{-2}{15}<\dfrac{-1}{10}<\dfrac{1}{6}<\dfrac{1}{5}<\dfrac{4}{15}<\dfrac{1}{3}<\dfrac{-2}{-5}$
