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Câu hỏi: Nếu $\int\limits_{1}^{2}{f\left( x \right)\text{d}x}=2$ và $\int\limits_{2}^{5}{f\left( x \right)\text{d}x}=5$ thì $\int\limits_{1}^{5}{f\left( x \right)\text{d}x}$ bằng
A. $7$
B. $3$
C. $-3$
D. $10$
A. $7$
B. $3$
C. $-3$
D. $10$
Ta có: $\int\limits_{1}^{5}{f\left( x \right)\text{d}x}=\int\limits_{1}^{2}{f\left( x \right)\text{d}x}+\int\limits_{2}^{5}{f\left( x \right)\text{d}x}$ $=2+5=7$.
Đáp án A.