(1)∵f(0)=c=0
∴c=0,
f′(x)=2ax+b=2x+1
∴a=1,b=1
(2)依题意可知an=(n+1)(n+2)-n(n+1)+1=2(n+1)+1,an+1=(n+2)(n+3)-(n+1)(n+2)+1=2(n+2)+1,
∴a(n+1)-an=2,a1=5
∴数列{an}是以5为首项,2为公差的等差数列,
∴an=5+(n-1)×2=2n+3
(3)bn=
=2
anan+1
-1 2n+3
,{bn}的前n项和 Sn=1 2n+5
-1 5
+1 7
-1 7
+…+1 9
--1 2n+3
=1 2n+5
--1 5
=1 2n+5
2n 5(2n+5)