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Câu hỏi: Hàm số $f(x)={{\log }_{2}}\left( {{x}^{2}}-2 \right)$ có đạo hàm là
A. ${f}'(x)=\dfrac{1}{\left( {{x}^{2}}-2 \right)\ln 2}$.
B. ${f}'(x)=\dfrac{2x}{\left( {{x}^{2}}-2 \right)\ln 2}$.
C. ${f}'(x)=\dfrac{2x\ln 2}{{{x}^{2}}-3}$.
D. ${f}'(x)=\dfrac{\ln 2}{{{x}^{2}}-2}$.
A. ${f}'(x)=\dfrac{1}{\left( {{x}^{2}}-2 \right)\ln 2}$.
B. ${f}'(x)=\dfrac{2x}{\left( {{x}^{2}}-2 \right)\ln 2}$.
C. ${f}'(x)=\dfrac{2x\ln 2}{{{x}^{2}}-3}$.
D. ${f}'(x)=\dfrac{\ln 2}{{{x}^{2}}-2}$.
$f\left( x \right)={{\log }_{2}}\left( {{x}^{2}}-2 \right)\Rightarrow f'\left( x \right)=\dfrac{\left( {{x}^{2}}-2 \right)'}{\left( {{x}^{2}}-2 \right).\ln 2}=\dfrac{2x}{\left( {{x}^{2}}-2 \right).\ln 2}$
Đáp án B.