• 试题 ID 27624


设 $f(x, y)=\int_0^{x y} e ^{-t^2} d t$ ,求 $\frac{x}{y} \frac{\partial^2 f}{\partial x^2}-2 \frac{\partial^2 f}{\partial x \partial y}+\frac{y}{x} \frac{\partial^2 f}{\partial y^2}$ .
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