设f(x)=ax+b
3f(x+1)-2f(x-1)
=3a(x+1)+3b-［2a(x-1)+2b］
=3ax+3a+3b-2ax+2a-2b
=ax+5a+b
=2x+17
所以,a=2
5a+b=17,b=7
f(x)=2x+7