(1)f(x)在区间[0,正无穷)上为单调增函数,理由:
f(1)=a+b+c=0,且a>b>c,所以a>0,c-(a+c)=b≥0,(4/a^2)(b^2-ac)=(4/a^2)(a^2+ac+c^2)
=4(c/a+1/2)^2+3,(-2