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Câu hỏi: Nếu $\int\limits_{0}^{2}{\left( f\left( x \right)+2x \right)}\text{d}x=13$ thì $\int\limits_{0}^{2}{f\left( x \right)}\text{d}x$ bằng
A. 9.
B. $-1$.
C. 1.
D. $-9$.
A. 9.
B. $-1$.
C. 1.
D. $-9$.
$13=\int\limits_{0}^{2}{\left( f\left( x \right)+2x \right)}\text{d}x=\int\limits_{0}^{2}{f\left( x \right)}\text{d}x+\left. {{x}^{2}} \right|_{0}^{2}=\int\limits_{0}^{2}{f\left( x \right)}\text{d}x+4$ $\Rightarrow \int\limits_{0}^{2}{f\left( x \right)}\text{d}x=9$.
Đáp án A.