4. Укажите неверное равенство. 1) \(\frac{14}{21} = \frac{2}{3}\) 2) \(\frac{48}{56} = \frac{6}{7}\) 3) \(\frac{54}{90} = \frac{3}{5}\) 4) \(\frac{21}{27} = \frac{7}{8}\)

1. \(\frac{14}{21} = \frac{2 \cdot 7}{3 \cdot 7} = \frac{2}{3}\) – верно.
2. \(\frac{48}{56} = \frac{6 \cdot 8}{7 \cdot 8} = \frac{6}{7}\) – верно.
3. \(\frac{54}{90} = \frac{3 \cdot 18}{5 \cdot 18} = \frac{3}{5}\) – верно.
4. \(\frac{21}{27} = \frac{7 \cdot 3}{9 \cdot 3} = \frac{7}{9}
   e \frac{7}{8}\) – неверно.

Ответ: 4)