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Câu hỏi: Nếu $\int\limits_{1}^{2}{f\left( x \right)\text{d}x}=-2$ và $\int\limits_{2}^{3}{f\left( x \right)\text{d}x}=1$ thì $\int\limits_{1}^{3}{f\left( x \right)\text{d}x}$ bằng
A. $-3$.
B. $-1$.
C. $1$.
D. $3$.
Ta có $\int\limits_{1}^{3}{f\left( x \right)\text{d}x}=\int\limits_{1}^{2}{f\left( x \right)\text{d}x}+\int\limits_{2}^{3}{f\left( x \right)\text{d}x}=-2+1=-1$.
A. $-3$.
B. $-1$.
C. $1$.
D. $3$.
Ta có $\int\limits_{1}^{3}{f\left( x \right)\text{d}x}=\int\limits_{1}^{2}{f\left( x \right)\text{d}x}+\int\limits_{2}^{3}{f\left( x \right)\text{d}x}=-2+1=-1$.
Đáp án B.