488 б) \(\frac{5}{12}b\) при \(b = \frac{1}{5}\), \(b = \frac{5}{12}\), \(b = \frac{6}{5}\), \(b = \frac{84}{25}\), \(b = 0\)

Решение: 1) Если \(b = \frac{1}{5}\), то \(\frac{5}{12} \cdot \frac{1}{5} = \frac{5 \cdot 1}{12 \cdot 5} = \frac{5}{60}\). Сократим дробь на 5: \(\frac{5:5}{60:5} = \frac{1}{12}\). 2) Если \(b = \frac{5}{12}\), то \(\frac{5}{12} \cdot \frac{5}{12} = \frac{5 \cdot 5}{12 \cdot 12} = \frac{25}{144}\). 3) Если \(b = \frac{6}{5}\), то \(\frac{5}{12} \cdot \frac{6}{5} = \frac{5 \cdot 6}{12 \cdot 5} = \frac{30}{60}\). Сократим дробь на 30: \(\frac{30:30}{60:30} = \frac{1}{2}\). 4) Если \(b = \frac{84}{25}\), то \(\frac{5}{12} \cdot \frac{84}{25} = \frac{5 \cdot 84}{12 \cdot 25} = \frac{420}{300}\). Сократим дробь на 60: \(\frac{420:60}{300:60} = \frac{7}{5}\). 5) Если \(b = 0\), то \(\frac{5}{12} \cdot 0 = 0\). Ответ: \(\frac{1}{12}\), \(\frac{25}{144}\), \(\frac{1}{2}\), \(\frac{7}{5}\), \(0\).