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#3选择题来源:303-2024
已知$f(x,y)$连续, 则$\int_{\frac{\pi}{6}}^{\frac{\pi}{2}}\mathrm{d}x\int_{\sin x}^{1}f(x,y)\mathrm{d}y=$
  • A. $\int_{\frac{1}{2}}^{1}\mathrm{d}y\int_{\frac{\pi}{6}}^{\arcsin y}f(x,y)\mathrm{d}x$
  • B. $\int_{\frac{1}{2}}^{1}\mathrm{d}y\int_{\frac{\pi}{2}}^{\arcsin y}f(x,y)\mathrm{d}x$
  • C. $\int_{0}^{\frac{1}{2}}\mathrm{d}y\int_{\frac{\pi}{6}}^{\arcsin y}f(x,y)\mathrm{d}x$
  • D. $\int_{0}^{\frac{1}{2}}\mathrm{d}y\int_{\frac{\pi}{2}}^{\arcsin y}f(x,y)\mathrm{d}x$
#4选择题来源:301-2025
设函数 $f(x,y)$ 连续, 则 $\int_{-2}^{2} dx \int_{4-x^2}^{4} f(x,y) dy =$
  • A. $\int_{0}^{4} \left[ \int_{-2}^{-\sqrt{4-y}} f(x,y)dx + \int_{\sqrt{4-y}}^{2} f(x,y)dx \right] dy$
  • B. $\int_{0}^{4} \left[ \int_{-2}^{\sqrt{4-y}} f(x,y)dx + \int_{\sqrt{4-y}}^{2} f(x,y)dx \right] dy$
  • C. $\int_{0}^{4} \left[ \int_{-2}^{-\sqrt{4-y}} f(x,y)dx + \int_{2}^{\sqrt{4-y}} f(x,y)dx \right] dy$
  • D. $2 \int_{0}^{4} dy \int_{\sqrt{4-y}}^{2} f(x,y)dx$
#5选择题来源:302-2025
设函数 $f(x,y)$ 连续,则 $\int_{-2}^{2} dx\int_{4-x^{2}}^{4} f(x,y)\,dy=(\ )$
  • A. $\int_{0}^{4}\left[\int_{-2}^{-\sqrt{4-y}} f(x,y)\,dx+\int_{\sqrt{4-y}}^{2} f(x,y)\,dx\right]dy$
  • B. $\int_{0}^{4}\left[\int_{-2}^{\sqrt{4-y}} f(x,y)\,dx+\int_{\sqrt{4-y}}^{2} f(x,y)\,dx\right]dy$
  • C. $\int_{0}^{4}\left[\int_{-2}^{-\sqrt{4-y}} f(x,y)\,dx+\int_{2}^{\sqrt{4-y}} f(x,y)\,dx\right]dy$
  • D. $2\int_{0}^{4} dy\int_{\sqrt{4-y}}^{2} f(x,y)\,dx$
#7选择题来源:302-2026
设函数 $f(x,y)$ 在区域 $D = \{(x,y) \mid 0 \leq x \leq y \leq 1\}$ 上连续,且满足对称性 $f(x,y) = f(y,x)$,则 $$\iint_{D} f(x,y) dxdy = \int_{0}^{1} \int_{0}^{y} f(x,y) dxdy$$
  • A. $2\lim\limits_{n \to \infty} \sum\limits_{i=1}^{n} \sum\limits_{j=n+1}^{n} f\left(\dfrac{i}{n}, \dfrac{j}{n}\right) \dfrac{1}{n^2}$
  • B. $\dfrac{1}{2}\lim\limits_{n \to \infty} \sum\limits_{i=1}^{n} \sum\limits_{j=1}^{n} f\left(\dfrac{i}{n}, \dfrac{j}{n}\right) \dfrac{1}{n^2}$
  • C. $2\lim\limits_{n \to \infty} \sum\limits_{i=1}^{2n} \sum\limits_{j=1}^{2n+1-i} f\left(\dfrac{i}{2n}, \dfrac{j}{2n}\right) \dfrac{1}{n^2}$
  • D. $\dfrac{1}{2}\lim\limits_{n \to \infty} \sum\limits_{i=1}^{2n} \sum\limits_{j=1}^{i} f\left(\dfrac{i}{2n}, \dfrac{j}{2n}\right) \dfrac{1}{n^2}$
#14填空题来源:303-2022
已知函数$f(x) = \begin{cases} e^x, & 0 \leqslant x \leqslant 1, \\ 0, & \text{其他}, \end{cases}$则$\int_{-\infty}^{+\infty} \mathrm{d}x \int_{-\infty}^{+\infty} f(x) f(y - x) \mathrm{d}y = \underline{\qquad}.$
#20解答题来源:301-2021
设 $D\subset\mathbb{R}^2$ 是有界单连通闭区域,$I(D)=\iint_D(4-x^2-y^2)dxdy$ 取得最大值的积分区域为 $D_1$。(I) 求 $I(D_1)$ 的值;(II) 计算 $\int_{\partial D_1}\frac{(xe^{x^2+4y^2}+y)dx+(4ye^{x^2+4y^2}-x)dy}{x^2+4y^2}$,其中 $\partial D_1$ 是 $D_1$ 的正向边界。