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Câu hỏi: Nếu $\int\limits_{0}^{2}{f\left( x \right)}\text{d}x=4$ thì $\int\limits_{0}^{2}{3f\left( x \right)}\text{d}x$ bằng
A. $\dfrac{3}{4}$.
B. $\dfrac{4}{3}$.
C. $7$.
D. $12$.
A. $\dfrac{3}{4}$.
B. $\dfrac{4}{3}$.
C. $7$.
D. $12$.
Vì $\int\limits_{0}^{2}{f\left( x \right)}\text{d}x=4$ nên $\int\limits_{0}^{2}{3f\left( x \right)}\text{d}x=3.4=12$.
Đáp án D.