设函数Z=f(u),u=x平方+Y平方且f(u)二阶导数,则偏x偏y是多少?
<p>问题：设函数Z=f(u),u=x平方+Y平方且f(u)二阶导数,则偏x偏y是多少?<p>答案：↓↓↓<p class="nav-title mt10" style="border-top:1px solid #ccc;padding-top: 10px;">李晓雷的回答：<div class="content-b">网友采纳 偏导符号不好打……但是又要和微分符号区分,所以我就用q代替了…… qz/qx =(df(u)/du)*(qu/qx) =f'(u)*(qu/qx) =f'(u)*2x q(qz/qx)/qy =q(f'(u)*2x)/qy =2x*q(f'(u))/qy =2x*(df'/du)*(qu/qy) =2x*f''(u)*2y =4xy*f''(u)
页:
[1]