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Câu hỏi: Cho $a$ là số thực dương tùy ý, khi đó ${{\log }_{2}}\left( \dfrac{{{a}^{5}}}{2\sqrt{2}} \right)$ bằng
A. $\dfrac{3}{2}-5{{\log }_{2}}a$.
B. $\dfrac{3}{2}+5{{\log }_{2}}a$.
C. $5{{\log }_{2}}a-\dfrac{2}{3}$.
D. $5{{\log }_{2}}a-\dfrac{3}{2}$.
A. $\dfrac{3}{2}-5{{\log }_{2}}a$.
B. $\dfrac{3}{2}+5{{\log }_{2}}a$.
C. $5{{\log }_{2}}a-\dfrac{2}{3}$.
D. $5{{\log }_{2}}a-\dfrac{3}{2}$.
${{\log }_{2}}\left( \dfrac{{{a}^{5}}}{2\sqrt{2}} \right)={{\log }_{2}}{{a}^{5}}-{{\log }_{2}}2\sqrt{2}=5{{\log }_{2}}a-\dfrac{3}{2}$.
Đáp án D.