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Câu hỏi: Cho $\int\limits_{-2}^{1}{f\left( x \right)\text{d}x}=3$. Tính tích phân $\int\limits_{-2}^{1}{\left[ 2f\left( x \right)-1 \right]\text{d}x}$.
A. $-3$.
B. $9$.
C. $5$.
D. $3$.
A. $-3$.
B. $9$.
C. $5$.
D. $3$.
Ta có $\int\limits_{-2}^{1}{\left[ 2f\left( x \right)-1 \right]\text{d}x}=2\int\limits_{-2}^{1}{f\left( x \right)\text{d}x}-\int\limits_{-2}^{1}{\text{d}x}=2.3-\left. x \right|_{-2}^{1}=2.3-3=3$.
Đáp án D.