302 Найдите произведение: a) 14/17 * 34/63; б) 35/8 * 16/7; в) 51/103 * 103/119; г) 4/15 * 30/49 * 7/8; д) 24 * 11/48; e) 6 * 3 5/6; 03 Выполните умножение: a) 3 3/4 * 1 3/5; б) 1 7/23 * 3 5/6; в) 1 15/29 * 1 9/20; г) 8 23/34 * 17/59; д) 2 1/3 * 1 4/5 * 1 4/7; e) 1 4/9 * 3 6/7 * 3 6/13. 04 Найдите значение выражения: а) 3/7 a при a = 3/7; a = 1/2; a = 2 1/7; a = 2 1/3; a= 28/33 б) 5/12 b при b = 1/5; b = 5/12; b = 1 1/5; b = 2 2/5

302. Найдите произведение: а) $$rac{14}{17} cdot rac{34}{63} = rac{2 cdot 7}{17} cdot rac{2 cdot 17}{9 cdot 7} = rac{2 cdot 2}{9} = rac{4}{9}$$ б) $$rac{35}{8} cdot rac{16}{7} = rac{5 cdot 7}{8} cdot rac{2 cdot 8}{7} = 5 cdot 2 = 10$$ в) $$rac{51}{103} cdot rac{103}{119} = rac{51}{119} = rac{3 cdot 17}{7 cdot 17} = rac{3}{7}$$ г) $$rac{4}{15} cdot rac{30}{49} cdot rac{7}{8} = rac{4}{15} cdot rac{2 cdot 15}{7 cdot 7} cdot rac{7}{2 cdot 4} = rac{1}{7}$$ д) $$24 cdot rac{11}{48} = rac{24}{1} cdot rac{11}{2 cdot 24} = rac{11}{2} = 5 rac{1}{2}$$ е) $$6 cdot 3rac{5}{6} = 6 cdot rac{3 cdot 6 + 5}{6} = 6 cdot rac{18 + 5}{6} = 6 cdot rac{23}{6} = 23$$ 303. Выполните умножение: а) $$3rac{3}{4} cdot 1rac{3}{5} = rac{3 cdot 4 + 3}{4} cdot rac{1 cdot 5 + 3}{5} = rac{12 + 3}{4} cdot rac{5 + 3}{5} = rac{15}{4} cdot rac{8}{5} = rac{3 cdot 5}{4} cdot rac{2 cdot 4}{5} = 3 cdot 2 = 6$$ б) $$1rac{7}{23} cdot 3rac{5}{6} = rac{1 cdot 23 + 7}{23} cdot rac{3 cdot 6 + 5}{6} = rac{23 + 7}{23} cdot rac{18 + 5}{6} = rac{30}{23} cdot rac{23}{6} = rac{30}{6} = 5$$ в) $$1rac{15}{29} cdot 1rac{9}{20} = rac{1 cdot 29 + 15}{29} cdot rac{1 cdot 20 + 9}{20} = rac{29 + 15}{29} cdot rac{20 + 9}{20} = rac{44}{29} cdot rac{29}{20} = rac{44}{20} = rac{11 cdot 4}{5 cdot 4} = rac{11}{5} = 2rac{1}{5}$$ г) $$8rac{23}{34} cdot rac{17}{59} = rac{8 cdot 34 + 23}{34} cdot rac{17}{59} = rac{272 + 23}{34} cdot rac{17}{59} = rac{295}{34} cdot rac{17}{59} = rac{5 cdot 59}{2 cdot 17} cdot rac{17}{59} = rac{5}{2} = 2rac{1}{2}$$ д) $$2rac{1}{3} cdot 1rac{4}{5} cdot 1rac{4}{7} = rac{2 cdot 3 + 1}{3} cdot rac{1 cdot 5 + 4}{5} cdot rac{1 cdot 7 + 4}{7} = rac{6 + 1}{3} cdot rac{5 + 4}{5} cdot rac{7 + 4}{7} = rac{7}{3} cdot rac{9}{5} cdot rac{11}{7} = rac{7}{3} cdot rac{9}{5} cdot rac{11}{7} = rac{1}{3} cdot rac{9}{5} cdot rac{11}{1} = rac{1}{1} cdot rac{3}{5} cdot rac{11}{1} = rac{33}{5} = 6rac{3}{5}$$ е) $$1rac{4}{9} cdot 3rac{6}{7} cdot 3rac{6}{13} = rac{1 cdot 9 + 4}{9} cdot rac{3 cdot 7 + 6}{7} cdot rac{3 cdot 13 + 6}{13} = rac{9 + 4}{9} cdot rac{21 + 6}{7} cdot rac{39 + 6}{13} = rac{13}{9} cdot rac{27}{7} cdot rac{45}{13} = rac{13}{9} cdot rac{27}{7} cdot rac{45}{13} = rac{1}{1} cdot rac{3}{7} cdot rac{5}{1} = rac{3 cdot 5}{7} = rac{15}{7} = 2rac{1}{7}$$ 304. Найдите значение выражения: а) $$rac{3}{7} a$$ при $$a = rac{3}{7}$$; $$rac{3}{7} cdot rac{3}{7} = rac{3 cdot 3}{7 cdot 7} = rac{9}{49}$$ $$rac{3}{7} a$$ при $$a = rac{1}{2}$$; $$rac{3}{7} cdot rac{1}{2} = rac{3 cdot 1}{7 cdot 2} = rac{3}{14}$$ $$rac{3}{7} a$$ при $$a = 2rac{1}{7}$$; $$rac{3}{7} cdot 2rac{1}{7} = rac{3}{7} cdot rac{2 cdot 7 + 1}{7} = rac{3}{7} cdot rac{14 + 1}{7} = rac{3}{7} cdot rac{15}{7} = rac{3 cdot 15}{7 cdot 7} = rac{45}{49}$$ $$rac{3}{7} a$$ при $$a = 2rac{1}{3}$$; $$rac{3}{7} cdot 2rac{1}{3} = rac{3}{7} cdot rac{2 cdot 3 + 1}{3} = rac{3}{7} cdot rac{6 + 1}{3} = rac{3}{7} cdot rac{7}{3} = 1$$ $$rac{3}{7} a$$ при $$a = rac{28}{33}$$; $$rac{3}{7} cdot rac{28}{33} = rac{3}{7} cdot rac{4 cdot 7}{11 cdot 3} = rac{4}{11}$$ б) $$rac{5}{12} b$$ при $$b = rac{1}{5}$$; $$rac{5}{12} cdot rac{1}{5} = rac{1}{12}$$ $$rac{5}{12} b$$ при $$b = rac{5}{12}$$; $$rac{5}{12} cdot rac{5}{12} = rac{25}{144}$$ $$rac{5}{12} b$$ при $$b = 1rac{1}{5}$$; $$rac{5}{12} cdot 1rac{1}{5} = rac{5}{12} cdot rac{6}{5} = rac{1}{2}$$ $$rac{5}{12} b$$ при $$b = 2rac{2}{5}$$; $$rac{5}{12} cdot 2rac{2}{5} = rac{5}{12} cdot rac{12}{5} = 1$$ Ответы: 302. a) 4/9 б) 10 в) 3/7 г) 1/7 д) 5 1/2 е) 23 303. a) 6 б) 5 в) 2 1/5 г) 2 1/2 д) 6 3/5 е) 2 1/7 304. а) 9/49; 3/14; 45/49; 1; 4/11 б) 1/12; 25/144; 1/2; 1