Question

Đã trả lời bởi chuyên gia

Answer 1

a) $\frac{2}{5} \times \frac{9}{8}$ = $\frac{\overset{1}{2} \times 9}{5 \times \underset{4}{8}} = \frac{1 \times 9}{5 \times 4} = \frac{9}{20}$

$\frac{10}{7} \times \frac{21}{20}$ = $\frac{\overset{1}{10} \times \overset{3}{21}}{\underset{1}{7} \times \underset{2}{20}} = \frac{1 \times 3}{1 \times 2} = \frac{3}{2}$

$6 \times \frac{3}{4}$ = $\frac{\overset{3}{6} \times 3}{1 \times \underset{2}{4}} = \frac{3 \times 3}{1 \times 2} = \frac{9}{2}$

$\frac{9}{10} \times \frac{7}{3} \times \frac{5}{14}$ = $\frac{\overset{3}{9} \times \overset{1}{7} \times \overset{1}{5}}{\underset{2}{10} \times \underset{1}{3} \times \underset{2}{14}} = \frac{3 \times 1 \times 1}{2 \times 1 \times 2} = \frac{3}{4}$

b) $\frac{6}{5} : \frac{9}{20}$ $= \frac{6}{5} \times \frac{20}{9} = \frac{\overset{2}{6} \times \overset{4}{20}}{\underset{1}{5} \times \underset{3}{9}} = \frac{2 \times 4}{1 \times 3} = \frac{8}{3}$

$8 : \frac{16}{5}$ $= 8 \times \frac{5}{16} = \frac{\overset{1}{8} \times 5}{1 \times \underset{2}{16}} = \frac{1 \times 5}{1 \times 2} = \frac{5}{2}$

$\frac{21}{4} : 7$ $= \frac{21}{4} \times \frac{1}{7} = \frac{\overset{3}{21} \times 1}{4 \times \underset{1}{7}} = \frac{3 \times 1}{4 \times 1} = \frac{3}{4}$

$6 \times \frac{1}{12} : \frac{5}{2}$ = $6 \times \frac{1}{12} \times \frac{2}{5} = \frac{\overset{1}{6} \times 1 \times \overset{1}{2}}{1 \times \underset{1}{12} \times 5} = \frac{1 \times 1 \times 1}{1 \times 1 \times 5} = \frac{1}{5}$

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Answer 2