Google
Câu hỏi: Cho hàm số $f\left( x \right)$ liên tục trên $\mathbb{R}$ và $\int\limits_{0}^{6}{f\left( x \right)\text{d}x}=10$, thì $\int\limits_{0}^{3}{f\left( 2x \right)\text{d}x}$ bằng:.
A. $30$.
B. $20$.
C. $10$.
D. $5$.
Ta có: $\int\limits_{0}^{3}{f\left( 2x \right)\text{d}x}=\dfrac{1}{2}\int\limits_{0}^{3}{f\left( 2x \right)\text{2d}x}=\dfrac{1}{2}\int\limits_{0}^{3}{f\left( 2x \right)\text{d2}x}=\dfrac{1}{2}\int\limits_{0}^{6}{f\left( x \right)\text{d}x}=\dfrac{1}{2}10=5$.
A. $30$.
B. $20$.
C. $10$.
D. $5$.
Ta có: $\int\limits_{0}^{3}{f\left( 2x \right)\text{d}x}=\dfrac{1}{2}\int\limits_{0}^{3}{f\left( 2x \right)\text{2d}x}=\dfrac{1}{2}\int\limits_{0}^{3}{f\left( 2x \right)\text{d2}x}=\dfrac{1}{2}\int\limits_{0}^{6}{f\left( x \right)\text{d}x}=\dfrac{1}{2}10=5$.
Đáp án D.