复习巩固
1. 等差数列的通项公式是:
an = a1+ (n-1)d , (n∈N*)
2. 等差数列的简单性质是:
(1) an= ak+ (n-k)d , (n , k∈N*) . (2) {an}为等差数列 an= an-1+d . (3) 若m + n = p + q ,则am+ an= ap+ aq