5.516 Найдите произведение: а) 10⋅1/10; б) 1/6⋅6; в) 5/9⋅9/5; г) 3/8⋅8/3.

а) \[10 \cdot \frac{1}{10} = \frac{10}{1} \cdot \frac{1}{10} = \frac{10 \cdot 1}{1 \cdot 10} = \frac{10}{10} = 1\] б) \[\frac{1}{6} \cdot 6 = \frac{1}{6} \cdot \frac{6}{1} = \frac{1 \cdot 6}{6 \cdot 1} = \frac{6}{6} = 1\] в) \[\frac{5}{9} \cdot \frac{9}{5} = \frac{5 \cdot 9}{9 \cdot 5} = \frac{45}{45} = 1\] г) \[\frac{3}{8} \cdot \frac{8}{3} = \frac{3 \cdot 8}{8 \cdot 3} = \frac{24}{24} = 1\]