有一道sat的试题麻烦解答一下 The 3rd term of a geometric seq
问题描述：
有一道sat的试题麻烦解答一下 The 3rd term of a geometric seq
uence is -3,and the 6th term is （八分之三.）what is the 4th term of the sequence?
答
geometric sequence是等比级数 第二个数字是第一个乘以某个数字a,ar,ar^2 (表示r的2次方),ar^3,ar^4,ar^5 ...第三个是ar^2 = -3; 第六个是ar^5 = 3/8; 那么第六个除以第三个 就是r^3 = -1/8r就是-1/2所以第4个sequen...