Đáp án:
$a) <$
$b) <$
$c) <$
$d) >$
Giải thích các bước giải:
$a) \dfrac{-3}{7}=\dfrac{-3×5}{7×5}=\dfrac{-15}{35}$
$\dfrac{2}{-5}=\dfrac{-2}{5}=\dfrac{-2×7}{5×7}=\dfrac{-14}{35}$
Vì $\dfrac{-15}{35}<\dfrac{-14}{35}⇒\dfrac{-3}{7}<\dfrac{2}{-5}$
$b) \dfrac{52}{177}=\dfrac{52×17}{177×17}=\dfrac{884}{3009}$
$\dfrac{9}{17}=\dfrac{9×177}{17×177}=\dfrac{1593}{3009}$
Vì $\dfrac{884}{3009}<\dfrac{1593}{3009}⇒\dfrac{52}{177}<\dfrac{9}{17}$
$c) \dfrac{-6}{7}<0$
$\dfrac{19}{23}>0$
$⇒\dfrac{-6}{7}<\dfrac{19}{23}$
$d) \dfrac{-11}{23}=\dfrac{-11×21}{23×21}=\dfrac{-231}{483}$
$\dfrac{-13}{21}=\dfrac{-13×23}{21×23}=\dfrac{-299}{483}$
Vì $\dfrac{-231}{483}>\dfrac{-299}{483}⇒\dfrac{-11}{23}>\dfrac{-13}{21}$
