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.求f(x,y)=xsin(x+y)+ycos(x+y)的二级偏导数

题目详情
.求f(x,y) =xsin(x+y )+ yco s(x+y )的二 级偏 导数
▼优质解答
答案和解析
Zyy=-xsin(x+y)-sin(x+y)-sin(x+y)-ycos(x+y)= -2sin(x+y)-xsin(x+y)-ycos(x+y) Zyy=-xsin(x+y)-sin(x+y)-sin(x+y)-ycos(x+y)= -2sin(x+y)-xsin(x+y)-ycos(x+y)