4. Выполните умножение: a) \(\frac{3}{8}\) ·4; б) \(\frac{12}{13}\) ·26; в) \(\frac{11}{14}\)·0; г) \(\frac{7}{9}\) · \(\frac{18}{49}\); д) \(\frac{3}{25}\) · \(\frac{5}{12}\); ж) \(\frac{14}{15}\) · \(\frac{3}{7}\); з) 1\(\frac{1}{3}\) · \(\frac{5}{8}\); и) 2\(\frac{1}{5}\) · 2\(\frac{3}{11}\).

4. Выполните умножение:

a) \(\frac{3}{8}\) ·4 = \(\frac{3}{8}\) · \(\frac{4}{1}\) = \(\frac{3·4}{8·1}\) = \(\frac{12}{8}\) = \(\frac{3}{2}\) = 1\(\frac{1}{2}\)

Ответ: 1\(\frac{1}{2}\)

б) \(\frac{12}{13}\) ·26 = \(\frac{12}{13}\) · \(\frac{26}{1}\) = \(\frac{12·26}{13·1}\) = \(\frac{12·2·\cancel{13}}{\cancel{13}·1}\) = 24

Ответ: 24

в) \(\frac{11}{14}\)·0 = 0

Ответ: 0

г) \(\frac{7}{9}\) · \(\frac{18}{49}\) = \(\frac{7·18}{9·49}\) = \(\frac{\cancel{7}·2·\cancel{9}}{\cancel{9}·\cancel{7}·7}\) = \(\frac{2}{7}\)

Ответ: \(\frac{2}{7}\)

д) \(\frac{3}{25}\) · \(\frac{5}{12}\) = \(\frac{3·5}{25·12}\) = \(\frac{\cancel{3}·\cancel{5}}{5·\cancel{5}·4·\cancel{3}}\) = \(\frac{1}{20}\)

Ответ: \(\frac{1}{20}\)

ж) \(\frac{14}{15}\) · \(\frac{3}{7}\) = \(\frac{14·3}{15·7}\) = \(\frac{2·\cancel{7}·\cancel{3}}{5·\cancel{3}·\cancel{7}}\) = \(\frac{2}{5}\)

Ответ: \(\frac{2}{5}\)

з) 1\(\frac{1}{3}\) · \(\frac{5}{8}\) = \(\frac{4}{3}\) · \(\frac{5}{8}\) = \(\frac{4·5}{3·8}\) = \(\frac{\cancel{4}·5}{3·2·\cancel{4}}\) = \(\frac{5}{6}\)

Ответ: \(\frac{5}{6}\)

и) 2\(\frac{1}{5}\) · 2\(\frac{3}{11}\) = \(\frac{11}{5}\) · \(\frac{25}{11}\) = \(\frac{11·25}{5·11}\) = \(\frac{\cancel{11}·5·\cancel{5}}{\cancel{5}·\cancel{11}}\) = 5

Ответ: 5