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Câu hỏi: Cho $\int\limits_{0}^{1}{f(x)\text{d}x}=-3$ và $\int\limits_{0}^{1}{g(x)\text{d}x}=2$, khi đó $\int\limits_{0}^{1}{\left[ f\left( x \right)+2g\left( x \right) \right]\text{d}x}$ bằng
A. $1$.
B. $-1$.
C. $-7$.
D. $5$.
A. $1$.
B. $-1$.
C. $-7$.
D. $5$.
Ta có:
$\int\limits_{0}^{1}{\left[ f\left( x \right)+2g\left( x \right) \right]\text{d}x}=\int\limits_{0}^{1}{f\left( x \right)\text{d}x}+2\int\limits_{0}^{1}{g\left( x \right)\text{d}x}=-3+2.2=1$.
$\int\limits_{0}^{1}{\left[ f\left( x \right)+2g\left( x \right) \right]\text{d}x}=\int\limits_{0}^{1}{f\left( x \right)\text{d}x}+2\int\limits_{0}^{1}{g\left( x \right)\text{d}x}=-3+2.2=1$.
Đáp án A.