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Câu hỏi: Cho $\int_2^5 f(x) \mathrm{d} x=10$. Kết quả tích phân $\int_5^2[2-4 f(x)] \mathrm{d} x$ bằng
A. 36 .
B. 40 .
C. 32 .
D. 34.
A. 36 .
B. 40 .
C. 32 .
D. 34.
$
\begin{aligned}
& \int_5^2[2-4 f(x)] \mathrm{d} x=\int_5^2 2 \mathrm{~d} x-4 \int_5^2 \mathrm{f}(x) \mathrm{d} x=-\int_2^5 2 \mathrm{~d} x+4 \int_2^5 \mathrm{f}(x) \mathrm{d} x=\left.2 x\right|_5 ^2+4 \\
& \int_2^5 f(x) \mathrm{d} x=-6+4.10=34
\end{aligned}
$
\begin{aligned}
& \int_5^2[2-4 f(x)] \mathrm{d} x=\int_5^2 2 \mathrm{~d} x-4 \int_5^2 \mathrm{f}(x) \mathrm{d} x=-\int_2^5 2 \mathrm{~d} x+4 \int_2^5 \mathrm{f}(x) \mathrm{d} x=\left.2 x\right|_5 ^2+4 \\
& \int_2^5 f(x) \mathrm{d} x=-6+4.10=34
\end{aligned}
$
Đáp án D.