由于:
a(n+1)=2an+3
则有:
[a(n+1)+3]=2(an+3)
[a(n+1)+3]/(an+3)=2
则:{an+3}为公比为2的等比数列
则:
an+3
=(a1+3)*2^(n-1)
=4*2^(n-1)
=2^2*2^(n-1)
=2^(n+1)
则:
an=2^(n+1)-3 (n>=1)�Ǹ�����2ʲôn+1�����ú�����2的n+1次方