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Câu hỏi: Biết $\int\limits_{1}^{2}{f\left( x \right)\text{d}x}=2, \int\limits_{1}^{2}{g\left( x \right)\text{d}x}=3$. Khi đó $\int\limits_{1}^{2}{\left( f\left( x \right)-2g\left( x \right) \right)\text{d}x}$ bằng
A. 1.
B. 8.
C. $-4$.
D. $-1$.
A. 1.
B. 8.
C. $-4$.
D. $-1$.
Ta có $\int\limits_{1}^{2}{\left( f\left( x \right)-2g\left( x \right) \right)\text{d}x}=\int\limits_{1}^{2}{f\left( x \right)\text{d}x}-2\int\limits_{1}^{2}{g\left( x \right)\text{d}x}=2-2.3=-4$.
Đáp án C.