漂亮的房子嘉宾:What number comes next in following series ? 9,12,21,48

来源：百度文库编辑：高校问答时间：2024/05/02 09:42:01

What number comes next in following series ? 9,12,21,48

前一项减去5，再乘以3，得到后一项
12=(9-5)×3
21=(12-5)×3
48=(21-5)×3

那么接下来就是（48－5）×3＝129

前两个数差3,为3的一次方;第二个数和第三个数相差9,位3 的平方;第三个数与第四个数相差27,位3 得立方,所以我们能推断出第四个数和第五个数相差3得四次方,即81,所以48+81=129

129
a(n)=a(n-1)+3^n

129

What number comes next in following series ? 9,12,21,48 what tree comes in twos 实况足球背景音乐-what comes around What goes around comes around 什么意思? what goes up but never comes up what goes up but never comes down what goes up when rain comes down what comes down,but never goes up? what goes out but never comes back What gose around comes around.怎样翻译？