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Câu hỏi: Cho $\int\limits_{0}^{1}{f\left( x \right)\text{d}x}=-2$ và $\int\limits_{1}^{5}{\left( 2f\left( x \right) \right)\text{d}x}=6$ khi đó $\int\limits_{0}^{5}{f\left( x \right)\text{d}x}$ bằng:
A. $1$.
B. $2$.
C. $4$.
D. $3$.
A. $1$.
B. $2$.
C. $4$.
D. $3$.
$\int\limits_{1}^{5}{\left( 2f\left( x \right) \right)\text{d}x=6\Leftrightarrow \int\limits_{1}^{5}{f\left( x \right)\text{d}x=3}}$
$\int\limits_{0}^{5}{f\left( x \right)\text{d}x}=\int\limits_{0}^{1}{f\left( x \right)\text{d}x}+\int\limits_{1}^{5}{f\left( x \right)\text{d}x}=-2+3=1$
$\int\limits_{0}^{5}{f\left( x \right)\text{d}x}=\int\limits_{0}^{1}{f\left( x \right)\text{d}x}+\int\limits_{1}^{5}{f\left( x \right)\text{d}x}=-2+3=1$
Đáp án A.