Question

() = 2,5

Answer 1

Очевидно, дано задание: (2/5)^x = 2,5.

2,5 = 5/2 = (2/5)^(-1). Приравняем обе части при равных основаниях.

Ответ: х = -1.

Answer 2

It seems like you've provided an equation or expression without any context. Could you please clarify what you mean by "()" and its relationship with the numbers "2" and "5"?