由f(x+1)=x^2-4,知a1=f(x-1)=(x-2)^2-4,a3=f(x)=(x-1)^2-4
又由2a2=a1+a3,可解的:x=0 x=3
1、当x=0时,a1=0,a2=-1.5,则an=-1.5n+1.5,S26=-4875.5
2、当x=3时,a1=-3,a2=-1.5,则an=1.5n-4.5,S26=448.5
由f(x+1)=x^2-4,知a1=f(x-1)=(x-2)^2-4,a3=f(x)=(x-1)^2-4
又由2a2=a1+a3,可解的:x=0 x=3
1、当x=0时,a1=0,a2=-1.5,则an=-1.5n+1.5,S26=-4875.5
2、当x=3时,a1=-3,a2=-1.5,则an=1.5n-4.5,S26=448.5