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Câu hỏi: Biết $\int\limits_{0}^{1}{\left[ f\left( x \right)+2x \right]dx=3}$, khi đó $\int\limits_{0}^{1}{f\left( x \right)dx}$ bằng
A. $1$.
B. $5$.
C. $3$.
D. $2$.
A. $1$.
B. $5$.
C. $3$.
D. $2$.
Ta có : $\int\limits_{0}^{1}{\left[ f\left( x \right)+2x \right]dx=3}\Leftrightarrow \int\limits_{0}^{1}{f\left( x \right)dx+\left. {{x}^{2}} \right|_{0}^{1}=3}\Leftrightarrow \int\limits_{0}^{1}{f\left( x \right)dx=2}$.
Đáp án D.