先证明bn=b^n/2^n=(b/2)^n (1)bn-1=(b/2)^(n-1) (2)(1)÷(2)bn/bn-1=b/2,是定值所以bn是等比数列计算anan=2an-1+2^(n+1)an=2an-1+2*2^n两边都除以2^2an/2^n-an-1*2/2^n=2an/2^n-an-1/2^(n-1)=2另Cn=an/2^n (n>=2)Cn...