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Câu hỏi: Cho $\int\limits_{- 2}^{5}{f(x) \text{d}x=8}$ và $\int\limits_{5}^{- 2}{g(x) \text{d}x=3}$. Khi đó, $\int\limits_{- 2}^{5}{\left[ f(x)-4g(x) \right]\text{d}x}$ bằng
A. $20$.
B. $12$.
C. $11$.
D. $5$.
A. $20$.
B. $12$.
C. $11$.
D. $5$.
Ta có: $\int\limits_{- 2}^{5}{\left[ f(x)-4g(x) \right]\text{d}x}=\int\limits_{- 2}^{5}{f(x) \text{d}x}-4\int\limits_{- 2}^{5}{g(x) \text{d}x} =\int\limits_{- 2}^{5}{f(x) \text{d}x}+4\int\limits_{5}^{- 2}{g(x) \text{d}x} =8+4.3=20$.
Đáp án A.