...具有二阶连续偏导,f(1,1)=2为f(u,v)的极值,z=f(x+y,f(x,y)),求...
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发布时间：7小时前
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热心网友
时间：6小时前
zx'=f'1(x+y,f(x,y)) + f'2(x+y,f(x,y)) * f'1(x,y)
zxy''= f''11(x+y,f(x,y)) + f''12(x+y,f(x,y))*f'2(y) + f'1(x,y) * [f''21(x+y,f(x,y)) + f''22(x+y,f(x,y)) * f'2(y)]
=f''11(x+y,f(x,y)) + f''12(x+y,f(x,y))*(f'1(x) + f'2(y)) + f'1(x) * f'2(y) * f''22(x+y,f(x,y))
热心网友
时间：6小时前
zx'=f'1(x+y,f(x,y)) + f'2(x+y,f(x,y)) * f'1(x,y)
zxy''= f''11(x+y,f(x,y)) + f''12(x+y,f(x,y))*f'2(y) + f'1(x,y) * [f''21(x+y,f(x,y)) + f''22(x+y,f(x,y)) * f'2(y)]
=f''11(x+y,f(x,y)) + f''12(x+y,f(x,y))*(f'1(x) + f'2(y)) + f'1(x) * f'2(y) * f''22(x+y,f(x,y))
