设函数z=yln(xy),求出两个一阶偏导数和四个二阶偏导数

如题所述

第1个回答  2015-01-14
z = yln(xy)
∂z/∂x = y²/(xy) = y/x
∂z/∂y = ln(xy)+xy/(xy) = ln(xy) +1
∂z²/∂x² = -y/x²
∂z²/∂x∂y = ∂z²/∂y∂x = 1/x
∂z²/∂y² = x/(xy) = 1/y

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