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Câu hỏi: Cho $\int\limits_{0}^{\dfrac{\pi }{2}}{f\left( x \right)dx}=5.$ Tích phân $\int\limits_{0}^{\dfrac{\pi }{2}}{\left[ \cos x+f\left( x \right) \right]dx}$ bằng
A. 4.
B. 8.
C. 6.
D. 7.
A. 4.
B. 8.
C. 6.
D. 7.
Ta có $\int\limits_{0}^{\dfrac{\pi }{2}}{\left[ \cos x+f\left( x \right) \right]dx}=\int\limits_{0}^{\dfrac{\pi }{2}}{\cos xdx+\int\limits_{0}^{\dfrac{\pi }{2}}{f\left( x \right)dx}=\sin x\left| _{\begin{smallmatrix}
\\
0
\end{smallmatrix}}^{\dfrac{\pi }{2}} \right.+5=6.}$
\\
0
\end{smallmatrix}}^{\dfrac{\pi }{2}} \right.+5=6.}$
Đáp án C.