Bài 74: trang 39 sgk Toán 6 tập 2
Điền các số thích hợp vào bảng sau:
| $a$ | $\frac{-2}{3}$ | $\frac{4}{15}$ | $\frac{9}{4}$ | $\frac{5}{8}$ | $\frac{4}{5}$ | $\frac{4}{15}$ | $0$ | $\frac{13}{19}$ | $\frac{-5}{11}$ | $\frac{}{}$ |
| $b$ | $\frac{4}{5}$ | $\frac{5}{8}$ | $\frac{-2}{3}$ | $\frac{4}{15}$ | $\frac{-2}{3}$ | $1$ | $\frac{-6}{13}$ | $\frac{}{}$ | $\frac{}{}$ | $\frac{-19}{43}$ |
| $a.b$ | $\frac{}{}$ | $\frac{}{}$ | $\frac{}{}$ | $\frac{}{}$ | $\frac{}{}$ | $\frac{}{}$ | $\frac{}{}$ | $\frac{13}{19}$ | $0$ | $0$ |
Bài Làm:
| $a$ | $\frac{-2}{3}$ | $\frac{4}{15}$ | $\frac{9}{4}$ | $\frac{5}{8}$ | $\frac{4}{5}$ | $\frac{4}{15}$ | $0$ | $\frac{13}{19}$ | $\frac{-5}{11}$ | $0$ |
| $b$ | $\frac{4}{5}$ | $\frac{5}{8}$ | $\frac{-2}{3}$ | $\frac{4}{15}$ | $\frac{-2}{3}$ | $1$ | $\frac{-6}{13}$ | $1$ | $0$ | $\frac{-19}{43}$ |
| $a.b$ | $\frac{-8}{15}$ | $\frac{1}{6}$ | $\frac{-3}{2}$ | $\frac{1}{6}$ | $\frac{-8}{15}$ | $\frac{4}{15}$ | $0$ | $\frac{13}{19}$ | $0$ | $0$ |