Đáp án:
Giải thích các bước giải:
$\dfrac{-21}{-140}$=$\dfrac{3}{20}$
$\dfrac{13}{-75}$=$\dfrac{-13}{75}$
$\dfrac{-5²-5.3²}{5³+5².3²}$=$\dfrac{-26}{175}$
MSC là :2100
$\dfrac{3}{20}$=$\dfrac{315}{2100}$
$\dfrac{-13}{75}$=$\dfrac{-364}{2100}$
$\dfrac{-26}{175}$=$\dfrac{-312}{2100}$