9) log₃ 4 + log₅ 20,25

9) log₃ 4 + log₅ 20,25 = log₃ 4 + log₅ (2025/100) = log₃ 4 + log₅ (81/4) = log₃ 2² + log₅ (9/2)² = 2log₃ 2 + 2log₅ (9/2) = 2log₃ 2 + 2log₅ 4.5 = 2log₃ 2 + 2log₅ (9/2)

log₃ 4 + log₅ 20.25 = log₃ 4 + log₅ (81/4) = log₃ 4 + log₅ 81 - log₅ 4 = log₃ 4 + log₅ 3⁴ - log₅ 2² = log₃ 4 + 4log₅ 3 - 2log₅ 2 ≈ 1.2619 + 4(0.6826) - 2(0.4307) ≈ 1.2619 + 2.7304 - 0.8614 ≈ 3.1309

Ответ: 3.1309