Điền các số thích hợp vào bảng sau :
a | \(\dfrac{-3}{4}\) | \(\dfrac{5}{9}\) | \(\dfrac{-7}{25}\) | \(\dfrac{4}{7}\) | \(\dfrac{-4}{19}\) | \(\dfrac{-18}{15}\) | \(\dfrac{50}{21}\) | ||
b | \(\dfrac{4}{7}\) | \(\dfrac{-18}{15}\) | \(\dfrac{50}{21}\) | \(\dfrac{-3}{7}\) | \(\dfrac{-3}{4}\) | \(\dfrac{5}{9}\) | \(\dfrac{6}{13}\) | \(\dfrac{-7}{25}\) | |
a.b | \(1\) | \(\dfrac{-4}{19}\) | \(0\) |