形如B_n=(za+b)q~n称之为差比型数列,差比型数列的求和是数列的重点内容之一,也是难点。差比型数列就是形如B_n=a_nb_n,其中{a_n}是等差数列,如a_n=an+b;{b_n}是等比数列,如b_n=q~n,即B_n=(an+b)q~n(a≠0,q≠1)。目前,差比型数列的求和多采用的是错位相减法。这种方法的优点是方法直接,学生容易理解,但在将两式相减时容易出现错误,且数据 For example, B_n = (za + b) q ~ n is called difference type series. The summation of difference type series is one of the key contents of the series, which is also a difficult point. The difference type array is the form of B_n = a_nb_n, where {a_n} is an arithmetic progression, such as a_n = an + b; {b_n} is a geometric sequence such as b_n = q ~ n, q ~ n (a ≠ 0, q ≠ 1). At present, the sum of difference type series mostly adopts the dislocation subtraction method. The advantage of this approach is that the method is straightforward and easy to understand for the student, but errors are prone to occur when subtracting the two types, and the data