Ex 4 (J si K) dau coroana

j)
[tex]1 \frac{1}{3} \times \frac{3}{4} \\ \frac{3 \times 1 + 1}{3} \times \frac{3}{4} \\ \frac{4}{3} \times \frac{3}{4} = 1[/tex]
k)
[tex]3 \frac{4}{7} \times \frac{2}{15} \\ \frac{7 \times 3 + 4}{7} \times \frac{2}{15} \\ \frac{25}{7} \times \frac{2}{15} \\ \frac{5}{7} \times \frac{2}{3} \\ \frac{10}{21} [/tex]

j)
[tex]1\frac{1}{3 } \times \frac{3}{4} = \frac{4}{3} \times \frac{4}{3 } = 1[/tex]
k)
[tex]3\frac{4}{7} \times \frac{2}{15} = \frac{25}{7} \times \frac{2}{15} = \frac{5}{7} \times \frac{2}{3} = \frac{10}{21} [/tex]