fx=x+ax^2+blnx过P（1,0）0=1+a+b*0a=-1f(x)=x-x^2+blnxf'(x)=1-2x+b/xf'(1)=1-2+b=2b=3∴f(x)=x-x^2+3lnx(2)证明f(x)≤2x-2设g(x)=f(x)-(2x-2)=x-x^2+3lnx-2x+2=-x^2-x+3lnx+2定义域是x>0g'(x）=-2x-1+3/x=-(2x+3)(...