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f'(x)=(x+1)(x-2)=0
x=-1,x=2
f''=2x-1
f''(-1)=-3<0
å½æ°åæ大å¼ï¼æ以
x=-1
az/ax=y*x^(y-1)
az/ay=x^ylnx
1/y*y'=4x³
两边积åï¼å¾
lny=x^4+lnc
y=ce^(x^4)
x=0,y=4ä»£å ¥ï¼å¾
4=c
æ以ç¹è§£ä¸ºy=4e^(x^4)
au/ax=y/(1+x²y²),au/ay=x/(1+x²y²)
du=y/(1+x²y²)dx+x/(1+x²y²)dy
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åå¼=â«(1,e)lnxdx²/2
=x²/2lnx|(1,e)-â«(1,e)x/2dx
=e²/2-1/4x²|(1,e)
=e²/4+1/4
åå¼=f(x+b)|(a,b)
=f(2b)-f(a+b)