Giải câu 1 trang 48 sách toán VNEN lớp 4 tập 2

Giải câu 1 trang 48 sách toán VNEN lớp 4 tập 2.

a. $\frac{1}{3} - \frac{1}{4}$ ; $\frac{4}{5} - \frac{1}{3}$ ; $\frac{5}{3} - \frac{3}{2}$

$\frac{1}{3} - \frac{1}{4} = \frac{1 \times 4}{3 \times 4} - \frac{1 \times 3}{4 \times 3} = \frac{4}{12} - \frac{3}{12} = \frac{1}{12}$

$\frac{4}{5} - \frac{1}{3} = \frac{4 \times 3}{5 \times 3} - \frac{1 \times 5}{3 \times 5} = \frac{12}{15} - \frac{5}{15} = \frac{7}{15}$

$\frac{5}{3} - \frac{3}{2} = \frac{5 \times 2}{3 \times 2} - \frac{3 \times 3}{2 \times 3} = \frac{10}{6} - \frac{9}{6} = \frac{1}{6}$

b. $\frac{3}{2} - \frac{1}{4}$ ; $\frac{7}{6} - \frac{2}{3}$ ; $\frac{5}{4} - \frac{3}{8}$

$\frac{3}{2} - \frac{1}{4} = \frac{3 \times 2}{2 \times 2} - \frac{1}{4} = \frac{6}{4} - \frac{1}{4} = \frac{5}{4}$

$\frac{7}{6} - \frac{2}{3} = \frac{7}{6} - \frac{2 \times 2}{3 \times 2} = \frac{7}{6} - \frac{4}{6} = \frac{3}{6}$

$\frac{5}{4} - \frac{3}{8} = \frac{5 \times 2}{4 \times 2} - \frac{3}{8} = \frac{10}{8} - \frac{3}{8} = \frac{7}{8}$

c. $\frac{7}{9} - \frac{1}{6}$ ; $\frac{5}{6} - \frac{5}{8}$ ; $\frac{7}{4} - \frac{5}{6}$

$\frac{7}{9} - \frac{1}{6} = \frac{7 \times 2}{9 \times 2} - \frac{1 \times 3}{6 \times 3} = \frac{14}{18} - \frac{3}{18} = \frac{11}{18}$

$\frac{5}{6} - \frac{5}{8} = \frac{5 \times 4}{6 \times 4} - \frac{5 \times 3}{8 \times 3} = \frac{20}{24} - \frac{15}{24} = \frac{5}{24}$

$\frac{7}{4} - \frac{5}{6} = \frac{7 \times 3}{4 \times 3} - \frac{5 \times 2}{6 \times 2} = \frac{21}{12} - \frac{10}{12} = \frac{11}{12}$