Đáp án:
Giải thích các bước giải:
a)
$\dfrac{-21}{28}$ = $\dfrac{-3}{4}$
$\dfrac{-39}{52}$ = $\dfrac{-3}{4}$
vậy $\dfrac{-21}{28}$ = $\dfrac{-39}{52}$
b)
$\dfrac{-1717}{2323}$= $\dfrac{-17}{23}$
$\dfrac{-171717}{232323}$ = $\dfrac{-17}{23}$
vậy $\dfrac{-1717}{2323}$ = $\dfrac{-171717}{232323}$