y=g(x)=1+c/(2x+1)
反函数时x=1+c/(2y+1)
c/(2y+1)=x-1
2y+1=c/(x-1)
2y=c/(x-1)-1=(c-x+1)/(x-1)
y=(-x/2+c/2+1/2)/(x-1)
即f(x)=a+3/(x-b)=(ax-ab+3)/(x-b)=(-x/2+c/2+1/2)/(x-1)
a=-1/2
-ab+3=c/2+1/2
b=1
则(c+1)/2=7/2
c=6
所以a=-1/2,b=1,c=6