有一列数,按一定规律排成1,-3,9,-27,81,-243,…,则第n个数是______.
问题描述:
有一列数,按一定规律排成1,-3,9,-27,81,-243,…,则第n个数是______.
答
(-3)^0=1
(-3)^1=-3
(-3)^2=9
(-3)^3=-27
(-3)^4=81
(-3)^5=-243
.
所以第n个数是(-3)^(N-1)