Question

обчислить
7_9 × 2_5 (дробь)
12_13 × 26_28 (дробь)
3 × 5_12 (дробь)
4 1_2 ×1 1_3 (дробь)

Спростити дробь
1 3_8 × 1 2_7m × 2_3 (дробь)


Обчислить
9 2_3 × 1,2 + 2 2_3 × 1,2 - 2 1_3 × 1,2 (дробь)​

Answer 1

$1) \: \displaystyle \frac{7}{9} \times \frac{2}{5 } = \frac{14}{45} \\ \\ 2) \: \: \frac{12}{13} \times \frac{26}{28} = \frac{3}{1} \times \frac{2}{7} = \frac{6}{7} \\ \\ 3) \: \: 3 \times \frac{5}{12} = \frac{3}{1} \times \frac{5}{12} = \frac{1}{1} \times \frac{5}{4} = \frac{5}{4} = 1.25 \\ \\4) \: \: 4 \frac{1}{2} \times 1 \frac{1}{3} = \frac{9}{2} \times \frac{4}{3} = \frac{3}{1} \times \frac{2}{1} = 3 \times 2 = 6 \\ \\ 5) \: \: 1 \frac{3}{8} \times 1 \frac{2}{7m} \times \frac{2}{3} = \frac{11}{8} \times 1\frac{2}{7m} \times \frac{2}{3} \\ \\ = \frac{22}{24} \times 1 \frac{2}{7m} = \frac{11}{12} \times 1 \frac{2}{7m} \\ \\ = \frac{11}{12}\times 1 \frac{2}{7} \times \frac{1}{m} = \frac{11}{12} \times \frac{9}{7} \times \frac{1}{m} = \frac{33}{28m} \\ \\ 6) \: \: 9 \frac{2}{3} \times 1.2 + 2 \frac{2}{3} \times 1.2 - 2 \frac{1}{3} \times 1.2 = \\ \\ \: \: \frac{29}{3} \times \frac{6}{5} + \frac{8}{3} \times \frac{6}{5} - \frac{7}{3} \times \frac{6}{5} = \\ \\ \frac{58}{5 } + \frac{16}{5} - \frac{14}{5} = \frac{60}{5} = 12$