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Câu hỏi: Nếu $\int\limits_{0}^{6}{f\left( x \right)\text{d}x}=5$ và $\int\limits_{0}^{6}{g\left( x \right)\text{d}x}=7$ thì $I=\int\limits_{0}^{6}{\left[ 2f\left( x \right)+3g\left( x \right) \right]\text{d}x}$ bằng
A. $26$.
B. $29$.
C. $31$.
D. $21$.
A. $26$.
B. $29$.
C. $31$.
D. $21$.
Ta có $I=\int\limits_{0}^{6}{\left[ 2f\left( x \right)+3g\left( x \right) \right]\text{d}x}=2\int\limits_{0}^{6}{f\left( x \right)\text{d}x}+3\int\limits_{0}^{6}{g\left( x \right)\text{d}x}=2.5+3.7=31$.
Đáp án C.