若数列﹛an﹜是公差为d的等差数列,则数列a1+a2,a3+a4,a5+a6·········是公差为多少的等差数列?由数列﹛an﹜是公差为d的等差数列,有通项为an=a1+(n-1)d,从而有 a(2n-1)=a1+[(2n-1)-1]d=a1+(2n-2)da2n=a1+(2n-...