一道偏导数题.高数.
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一道偏导数题.高数.一道偏导数题.高数.一道偏导数题.高数.lnf=(x-y)ln(x+y)两边对y求导f''y/f=-ln(x+y)+(x-y)/(x+y)=[(x-y)-(x+y)ln(x+y)]/
一道偏导数题.高数.
一道偏导数题.高数.
一道偏导数题.高数.
lnf=(x-y)ln(x+y)
两边对y求导
f'y/f= -ln(x+y)+(x-y)/(x+y)=[(x-y)-(x+y)ln(x+y)]/(x+y)
所以f'y=f(x,y)*[(x-y)-(x+y)ln(x+y)]/(x+y)=[(x+y)^(x-y-1)]*[(x-y)-(x+y)ln(x+y)]