Google
Câu hỏi: Cho $\int{\left( \dfrac{1}{x}+2x \right)\text{d}x}=f\left( x \right)+C$. Khẳng định nào dưới đây đúng?
A. ${f}'\left( x \right)=\dfrac{1}{x}+2x$ .
B. ${f}'\left( x \right)=-\dfrac{1}{{{x}^{2}}}+2$ .
C. ${f}'\left( x \right)=\dfrac{1}{{{x}^{2}}}+2$ .
D. ${f}'\left( x \right)=\ln x+{{x}^{2}}$ .
A. ${f}'\left( x \right)=\dfrac{1}{x}+2x$ .
B. ${f}'\left( x \right)=-\dfrac{1}{{{x}^{2}}}+2$ .
C. ${f}'\left( x \right)=\dfrac{1}{{{x}^{2}}}+2$ .
D. ${f}'\left( x \right)=\ln x+{{x}^{2}}$ .
Ta có: $\int{\left( \dfrac{1}{x}+2x \right)\text{d}x}=f\left( x \right)+C\Rightarrow {f}'\left( x \right)=\dfrac{1}{x}+2x$.
Đáp án A.