Đáp án:
a)
$\dfrac{23}{21}>\dfrac{23}{23}>\dfrac{21}{23}$
$\Rightarrow \dfrac{23}{21}>\dfrac{21}{23}$
b)
$\dfrac{-15}{-17}=\dfrac{15}{17}>0$
$\dfrac{16}{-19}<0$
$\Rightarrow \dfrac{-15}{-17}>\dfrac{16}{-19}$
c)
$\dfrac{59}{101}>\dfrac{59}{105}>\dfrac{56}{105}$
$\Rightarrow \dfrac{59}{101}>\dfrac{56}{105}$
d)
$\dfrac{14}{55}>\dfrac{14}{56}=\dfrac{21}{84}>\dfrac{19}{84}$
$\Rightarrow \dfrac{14}{55}>\dfrac{19}{84}$