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Câu hỏi: Cho $\int\limits_{2}^{5}{f\left( x \right)dx}=10.$ Khi đó $\int\limits_{5}^{2}{\left[ 2-4f\left( x \right) \right]dx}$ bằng
A. 32
B. 34
C. 42.
D. 46.
A. 32
B. 34
C. 42.
D. 46.
Ta có
$\int\limits_{5}^{2}{\left[ 2-4f\left( x \right) \right]dx}=\int\limits_{5}^{2}{2dx}-4\int\limits_{5}^{2}{f\left( x \right)dx}=2\left( 2-5 \right)-4.\left( -10 \right)=34.$
$\int\limits_{5}^{2}{\left[ 2-4f\left( x \right) \right]dx}=\int\limits_{5}^{2}{2dx}-4\int\limits_{5}^{2}{f\left( x \right)dx}=2\left( 2-5 \right)-4.\left( -10 \right)=34.$
Đáp án B.