设一列数a1 .a2 .a3 .….a100 中任意三个相邻数之和都是37,已知a2 = 25,a9 = 2x,a99 = 3 x,a100=

问题描述:

设一列数a1 .a2 .a3 .….a100 中任意三个相邻数之和都是37,已知a2 = 25,a9 = 2x,a99 = 3 x,a100=

设A1为A,A3为B,那么从A4往下就一直是A;25;B这样重复,即A9与A99都是B,即3x=2x,x就是0,也即是B为0,那么A即为12,所以A100也是12.