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Câu hỏi: Cho $a>0$ thỏa mãn $\text{log}a=\dfrac{1}{2}$. Tính $\text{log}\left( 1000\sqrt{a} \right)$.
A. $\dfrac{13}{4}$.
B. $4$.
C. $\dfrac{3}{4}$.
D. $\dfrac{3}{\sqrt{2}}$.
A. $\dfrac{13}{4}$.
B. $4$.
C. $\dfrac{3}{4}$.
D. $\dfrac{3}{\sqrt{2}}$.
Ta có $\text{log}\left( 1000\sqrt{a} \right)=\text{log}1000+\text{log}\sqrt{a}=3+\dfrac{1}{2}\text{log}a=3+\dfrac{1}{2}.\dfrac{1}{2}=\dfrac{13}{4}$.
Đáp án A.