1. log 25 35, если log5 7 = a. 2. решить: log3(log2 5×log5 8)

Задание 1.
log₂₅35 = (1/2) • log₅ • (5 • 7) = (1/2) • (log₅5 + log₅7) = (1/2) • (1 +log₅7) = (1/2) • (1 + a).

Задание 2.
log₃ • (log₂5 • log₅8) = log₃ • (log₂5 • log₅2³) = log₃ • (log₂5 • 3 • log₅2) = log₃(3 • log₂5/log₂5) = log₃3 = 1.