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Câu hỏi: Cho các số thực dương $a,b,a\ne 1$. Hãy chọn phương án đúng.
A. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=2{{\log }_{a}}b+1$.
B. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=-2{{\log }_{a}}b-1$.
C. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=2{{\log }_{a}}b-1$.
D. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=-2{{\log }_{a}}b+1$.
A. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=2{{\log }_{a}}b+1$.
B. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=-2{{\log }_{a}}b-1$.
C. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=2{{\log }_{a}}b-1$.
D. ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}=-2{{\log }_{a}}b+1$.
Ta có ${{\log }_{a}}\dfrac{{{b}^{2}}}{a}={{\log }_{a}}{{b}^{2}}-{{\log }_{a}}a=2{{\log }_{a}}b-1$.
Đáp án C.