此题颇具难度构造等比a(n+1)+k(n+1)+m=2(an+kn+m)其中k m 是待定系数2k-k=22m-m-k=0k=2 m=2所以 a(n+1)+2(n+1)+2=2(an+2n+2)所以 an+2n+2=2(a(n-1)+2(n-1)+2)所以an+2n+2=2^(n-1)*(a1+2*1+2)=5*2^(n-1)an=5*2^(n...