f'(x)=2ax-(a+2)+1/x=[2ax^2-(a+2)x+1]/x=(2x-1)(ax-1)/x,其中x>0
(1)当a=1时,f'(x)=(2x-1)(x-1)/x
∴f'(1)=0,而f(1)=1-3=-2
∴切线方程是:y+2=0
(2)当a>2时,1/a
f'(x)=2ax-(a+2)+1/x=[2ax^2-(a+2)x+1]/x=(2x-1)(ax-1)/x,其中x>0
(1)当a=1时,f'(x)=(2x-1)(x-1)/x
∴f'(1)=0,而f(1)=1-3=-2
∴切线方程是:y+2=0
(2)当a>2时,1/a