一、题目
设函数 $z$ $=$ $z(x,y)$ 由方程 $x – az$ $=$ $\mathrm{e}^{y+az}$($a$ 是非零常数)确定,则:
»A« $\frac{\partial z}{\partial x} – \frac{\partial z}{\partial y} = \frac{1}{a}$
»B« $\frac{\partial z}{\partial x} + \frac{\partial z}{\partial y} = \frac{1}{a}$
»C« $\frac{\partial z}{\partial x} – \frac{\partial z}{\partial y} = -\frac{1}{a}$
»D« $\frac{\partial z}{\partial x} + \frac{\partial z}{\partial y} = -\frac{1}{a}$



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