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Câu hỏi: Nếu $\int\limits_{0}^{3}{f\left( x \right)\text{d}x}=4,\int\limits_{0}^{3}{g\left( x \right)\text{d}x}=-3$ thì $\int\limits_{0}^{3}{\left[ f\left( x \right)-\text{2g}\left( x \right)\text{+2}x \right]\text{d}x}$ bằng
A. $3$.
B. $39$.
C. $19$.
D. $15$.
A. $3$.
B. $39$.
C. $19$.
D. $15$.
Ta có
$\int\limits_{0}^{3}{\left[ f\left( x \right)-\text{2g}\left( x \right)\text{+2}x \right]\text{d}x}=\int\limits_{0}^{3}{f\left( x \right)\text{d}x}-2\int\limits_{0}^{3}{g\left( x \right)\text{d}x}+\int\limits_{0}^{3}{2x\text{d}x}=4-2.\left( -3 \right)+9=19$.
$\int\limits_{0}^{3}{\left[ f\left( x \right)-\text{2g}\left( x \right)\text{+2}x \right]\text{d}x}=\int\limits_{0}^{3}{f\left( x \right)\text{d}x}-2\int\limits_{0}^{3}{g\left( x \right)\text{d}x}+\int\limits_{0}^{3}{2x\text{d}x}=4-2.\left( -3 \right)+9=19$.
Đáp án C.