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Câu hỏi: Nếu $\int\limits_{2}^{5}{f\left( x \right)}dx=3$ và $\int\limits_{2}^{5}{\left[ f\left( x \right)-g\left( x \right) \right]}dx=-2$ thì $\int\limits_{2}^{5}{g(x)dx}$ bằng
A. $1$.
B. $-5$.
C. $5$.
D. $-6$.
A. $1$.
B. $-5$.
C. $5$.
D. $-6$.
Ta có: $\int\limits_{2}^{5}{\left[ f\left( x \right)-g\left( x \right) \right]}dx=\int\limits_{2}^{5}{f\left( x \right)}dx-\int\limits_{2}^{5}{g\left( x \right)}dx=3-\int\limits_{2}^{5}{g\left( x \right)}dx=-2$. Suy ra: $\int\limits_{2}^{5}{g(x)=3+2=5}$.
Đáp án C.