Ответ:

а) Знаменатель 18:

\(\frac{4}{9}=\frac{4\cdot2}{9\cdot2}=\frac{8}{18}\), \(\frac{5}{6}=\frac{5\cdot3}{6\cdot3}=\frac{15}{18}\), \(\frac{7}{2}=\frac{7\cdot9}{2\cdot9}=\frac{63}{18}\).

б) Знаменатель 80:

\(\frac{7}{8}=\frac{7\cdot10}{8\cdot10}=\frac{70}{80}\), \(\frac{5}{16}=\frac{5\cdot5}{16\cdot5}=\frac{25}{80}\), \(\frac{21}{40}=\frac{21\cdot2}{40\cdot2}=\frac{42}{80}\).

1) НОЗ(3, 4) = 12:

\(\frac{1}{3}=\frac{4}{12}\), \(\frac{1}{4}=\frac{3}{12}\).

2) НОЗ(8, 16) = 16:

\(\frac{5}{8}=\frac{10}{16}\), \(\frac{3}{16}=\frac{3}{16}\).

в) НОЗ(8, 20) = 40:

\(\frac{5}{8}=\frac{25}{40}\), \(\frac{3}{20}=\frac{6}{40}\).

г) НОЗ(9, 24) = 72:

\(\frac{2}{9}=\frac{16}{72}\), \(\frac{7}{24}=\frac{21}{72}\).