a, \(\dfrac{17}{23}\ne\dfrac{1717}{-2323}\) vì:
\(\dfrac{1717}{-2323}=\dfrac{1717:101}{\left(-2323\right):101}=\dfrac{17}{-23}\)
và \(\dfrac{17}{23}\ne\dfrac{17}{-23}\) => Vậy \(\dfrac{17}{23}\ne\dfrac{1717}{-2323}\)
b, \(\dfrac{-31}{49}=\dfrac{-313131}{494949}\) vì:
\(\dfrac{-313131}{494949}=\dfrac{\left(-313131\right):10101}{494949:10101}=\dfrac{-31}{49}\)
và \(\dfrac{-31}{49}=\dfrac{-31}{49}\) => Vậy \(\dfrac{-31}{49}=\dfrac{-313131}{494949}\)