Google
Câu hỏi: Cho $\int\limits_{-1}^{1}{f\left( x \right)\text{d}x}=2$ và $\int\limits_{-1}^{1}{g\left( x \right)\text{d}x}=-7$, khi đó $\int\limits_{-1}^{1}{\left[ f\left( x \right)-\dfrac{1}{7}g\left( x \right) \right]\text{d}x}$ bằng
A. $-3$.
B. $-1$.
C. $3$.
D. $1$.
A. $-3$.
B. $-1$.
C. $3$.
D. $1$.
Ta có: $\int\limits_{-1}^{1}{\left[ f\left( x \right)-\dfrac{1}{7}g\left( x \right) \right]\text{d}x}=\int\limits_{-1}^{1}{f\left( x \right)\text{d}x}-\dfrac{1}{7}\int\limits_{-1}^{1}{g\left( x \right)\text{d}x}=2-\dfrac{1}{7}.\left( -7 \right)=3$.
Đáp án C.