Đáp án+Giải thích các bước giải:
$\begin{array}{|c|c|c|}\hline \dfrac{a}{b}&\dfrac{-3}{5}&\dfrac{4}{7}&\dfrac{-5}{13}&\text{0}&\text{Dòng 1}\\\hline -\dfrac{a}{b}&\dfrac{3}{5}&\dfrac{-4}{7}&\dfrac{5}{13}&\text{0}&\text{Dòng 2}\\\hline -(-\dfrac{a}{b})&\dfrac{-3}{5}&\dfrac{4}{7}&\dfrac{-5}{13}&\text{0}&\text{Dòng 3}\\\hline\end{array}$