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Câu hỏi: Nếu $\int\limits_{1}^{2}{f\left( x \right)}\text{d}x=2$ thì $\int\limits_{1}^{2}{\left[ 3f\left( x \right)-2 \right]}\text{d}x$ bằng
A. $1$.
B. $3$.
C. $2$.
D. $4$.
A. $1$.
B. $3$.
C. $2$.
D. $4$.
$\int\limits_{1}^{2}{\left[ 3f\left( x \right)-2 \right]}\text{d}x=3\int\limits_{1}^{2}{f\left( x \right)}dx-\int\limits_{1}^{2}{2}dx=3.2-2=4$.
Đáp án D.