Question

Помогите очень срочно нужно​

Answer 1

Ответ:

$log_{3}(4) \times log_{4}(5) \times log_{5}(7) \times log_{7}(81) = \\ = \frac{1}{ log_{4}(3) } \times log_{4}(5) \times log_{5}(7) \times log_{7}(81) = \\ = log_{3}(5) \times log_{5}(7) \times log_{7}(81) = \\ = \frac{1}{ log_{5}(3) } \times log_{5}(7) \times log_{7}(81) = \\ = log_{3}(7) \times log_{7}(81) = \frac{ log_{7}(81) }{ log_{7}(3) } = \\ = log_{3}(81) = 4$