已知1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 急...求1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 ..

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已知1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值急...求1-1/2(1/3-y)^2=2+|3-x|/2,求3x^

已知1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 急...求1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 ..
已知1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 急...
求1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 ..

已知1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 急...求1-1/2(1/3-y)^2=2+|3-x|/2,求3x^2y-[2xy^2-2(xy-3/2x^2y)+xy]+3xy^2的值 ..
错题一个

哥们儿，考试呢吧？

f(x,y)=x^3-y^3-3xy
分别对x,y求偏导:
fx=3x^2-3y
fy=-3y^2-3x.
令fx=0,fy=0,可得x=0,y=0,或x=-1,y=1这2个驻点.
然后求二阶偏导:
fxx=6x,fxy=-3,fyy=-6y.
x=0,y=0时,fxx=0,fxy=-3,fyy=0,(-3)^2-0>0,所以(0,0)不是极...

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f(x,y)=x^3-y^3-3xy
分别对x,y求偏导:
fx=3x^2-3y
fy=-3y^2-3x.
令fx=0,fy=0,可得x=0,y=0,或x=-1,y=1这2个驻点.
然后求二阶偏导:
fxx=6x,fxy=-3,fyy=-6y.
x=0,y=0时,fxx=0,fxy=-3,fyy=0,(-3)^2-0>0,所以(0,0)不是极值点;
x=-1,y=1时,fxx=-6,fxy=-3,fyy=-6,(-3)^2-(-6)^2<0,所以(-1,1)是极值点,且由于fxx<0,所以其为极大值.

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