偏导数fxx fxy类题目怎么解 求解题过程
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发布时间:2022-07-13 19:31
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热心网友
时间:2023-09-11 00:43
对某字母求偏导数,需要把其它字母看成常数 。
A、-4cos(2x+y)+sin(x-y)
B、-2cos(2x+y)-sin(x-y)
C、8sin(2x+y)+cos(x-y)
D、2sin(2x+y)+cos(x-y)
E、4sin(2x+y)-cos(x-y)
F、4sin(2x+y)-cos(x-y)
热心网友
时间:2023-09-11 00:43
∂f/∂x=fx=-4cos(2x+y)+sin(x-y)
∂f/∂y=fy=-2cos(2x+y)-sin(x-y)
∂²f/∂x²=fxx=8sin(2x+y)+cos(x-y)
∂²f/∂y²=fyy=2sin(2x+y)+cos(x-y)
∂²f/∂x∂y=fxy(原题这里写错!)=4sin(2x+y)-cos(x-y)
∂²f/∂y∂x=fyx(原题这里写错!)=4sin(2x+y)-cos(x-y)