设g(x)=f(x)e^x
=(ax^2+bx+c)e^x
g'(x)=(2ax+b)e^x+(ax^2+bx+c)e^x
=e^x[ax^2+(2a+b)x+b+c]
âµx=-1æ¯æå¼ç¹
â´g'(-1)=0
e^(-1)[a(-1)^2+(2a+b)(-1)+b+c]=0
1/e(a-2a-b+b+c)=0
1/e(c-a)=0
c-a=0
c=a
f(x)=ax^2+bx+a
=a[x+b/(2a)]^2+(4a^2-b^2)/(4a)
=a[x+b/(2a)]^2+[(2a+b)(2a-b)]/(4a)
è¥-b/(2a)=-1
b=2a
2a-b=0
f(x)è¿é¡¶ç¹(-1,0)
AãBæ¯å¯è½ç
è¥-b/(2a)=1
b=-2a
2a+b=0
f(x)è¿é¡¶ç¹(1,0)
èCå¾é¡¶ç¹ä¸æ¯(1,0)
å æ¤ï¼Cä¸å¯è½ã
è¥-b/(2a)=-2
b=4a
(4a^2-b^2)/(4a)
=[4a^2-(4a)^2]/(4a)
=-12a^2/(4a)
=-3a
âµDå¾a>0
â´-3a<0
Dæ¯å¯è½çã
综ä¸ï¼Cä¸å¯è½ã
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