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Câu hỏi: Nếu $\int\limits_{-1}^{2}{f\left( x \right)\text{d}x}=3,\int\limits_{-1}^{2}{g\left( x \right)\text{d}x}=5$ thì $\int\limits_{-1}^{2}{\left[ 2g\left( x \right)-3f\left( x \right) \right]\text{d}x}$ bằng
A. 6.
B. $1$.
C. $-9$.
D. $19$.
A. 6.
B. $1$.
C. $-9$.
D. $19$.
Xét $\int\limits_{-1}^{2}{\left[ 2g\left( x \right)-3f\left( x \right) \right]\text{d}x}=2\int\limits_{-1}^{2}{g\left( x \right)\text{d}x-3\int\limits_{-1}^{2}{f\left( x \right)\text{d}x}}=2.5-3.3=1$.Đáp án B.