ведение: 314.7; в) 725; г) 8.211; B) 74.61 15 19 4 +4 8' Д 61 19 4' г) 3-177-31.37. 14 29 14 значение выражения: 29 19. 17 B) C

Предмет: Математика

a) $$3\frac{9}{14} \cdot 7 = \frac{3 \cdot 14 + 9}{14} \cdot 7 = \frac{42 + 9}{14} \cdot 7 = \frac{51}{14} \cdot 7 = \frac{51 \cdot 7}{14} = \frac{51 \cdot 1}{2} = \frac{51}{2} = 25 \frac{1}{2}$$

в) $$7\frac{4}{27} \cdot 5 = \frac{7 \cdot 27 + 4}{27} \cdot 5 = \frac{189 + 4}{27} \cdot 5 = \frac{193}{27} \cdot 5 = \frac{193 \cdot 5}{27} = \frac{965}{27} = 35 \frac{20}{27}$$

г) $$8 \cdot 2\frac{1}{8} = 8 \cdot \frac{2 \cdot 8 + 1}{8} = 8 \cdot \frac{16 + 1}{8} = 8 \cdot \frac{17}{8} = \frac{8 \cdot 17}{8} = \frac{136}{8} = 17$$

B) $$7\frac{4}{19} \cdot 6\frac{1}{4} + 4\frac{15}{19} \cdot 6\frac{1}{4} = 6\frac{1}{4} \cdot (7\frac{4}{19} + 4\frac{15}{19}) = 6\frac{1}{4} \cdot (7 + 4 + \frac{4}{19} + \frac{15}{19}) = 6\frac{1}{4} \cdot (11 + \frac{19}{19}) = 6\frac{1}{4} \cdot (11 + 1) = 6\frac{1}{4} \cdot 12 = \frac{6 \cdot 4 + 1}{4} \cdot 12 = \frac{24 + 1}{4} \cdot 12 = \frac{25}{4} \cdot 12 = \frac{25 \cdot 12}{4} = \frac{25 \cdot 3}{1} = 75$$

г) $$3\frac{1}{14} \cdot 17\frac{7}{29} - 3\frac{1}{14} \cdot 3\frac{7}{29} = 3\frac{1}{14} \cdot (17\frac{7}{29} - 3\frac{7}{29}) = 3\frac{1}{14} \cdot (17 - 3 + \frac{7}{29} - \frac{7}{29}) = 3\frac{1}{14} \cdot 14 = \frac{3 \cdot 14 + 1}{14} \cdot 14 = \frac{42 + 1}{14} \cdot 14 = \frac{43}{14} \cdot 14 = 43$$