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Câu hỏi: Đạo hàm ${f}'\left( x \right)$ của hàm số $f\left( x \right)={{\log }_{5}}\left( 2\text{x}+3 \right)$ là
A. ${f}'\left( x \right)=\dfrac{1}{2\left( 2\text{x}+3 \right)\ln 5}$
B. ${f}'\left( x \right)=\dfrac{2}{\left( 2\text{x}+3 \right)\ln 5}$
C. ${f}'\left( x \right)=\dfrac{2}{2\text{x}+3}$
D. ${f}'\left( x \right)=\dfrac{2\ln 5}{\left( 2\text{x}+3 \right)}$
A. ${f}'\left( x \right)=\dfrac{1}{2\left( 2\text{x}+3 \right)\ln 5}$
B. ${f}'\left( x \right)=\dfrac{2}{\left( 2\text{x}+3 \right)\ln 5}$
C. ${f}'\left( x \right)=\dfrac{2}{2\text{x}+3}$
D. ${f}'\left( x \right)=\dfrac{2\ln 5}{\left( 2\text{x}+3 \right)}$
Ta có ${f}'\left( x \right)=\dfrac{{{\left( 2\text{x}+3 \right)}^{\prime }}}{\left( 2\text{x}+3 \right)\ln 5}=\dfrac{2}{\left( 2\text{x}+3 \right)\ln 5}$.
Đáp án B.