Cho a là số thực dương khác 1 . Mệnh đề nào dưới đây đúng? A. log_(sqrt [7](a))((1)/(a^9))=-(1)/(63) B. log_(sqrt [7](a))((1)/(a^9))=-63 C. log_(sqrt [7](a))((1)/(a^9))=63 D. log_(sqrt [7](a))((1)/(a^9))=(1)/(63)

To solve the problem, we need to determine which statement is true. The correct answer is D. .Explanation:We can rewrite the equation as .Using logarithmic properties, we can simplify further: Taking the reciprocal of both sides: Therefore, the correct statement is D. .