an+1=2an+1特征方程 x=2x+1 x=-1an+1-(-1)=2an+1-(-1)an+1+1=2(an+1)令bn=an+1bn+1=2bnbn+1 / bn=2bn为首项为2 公比为2的等比数列bn=2*2^(n-1)=2^nan=bn-1=(2^n)-1祝学习进步，求采纳~~
