观察下面的数:(1)-3,9,-27,81,-243,729.(2)0,12,-24,84,-243,729.(3)-1,3,-9,27,-81,243.

问题描述:

观察下面的数:(1)-3,9,-27,81,-243,729.(2)0,12,-24,84,-243,729.(3)-1,3,-9,27,-81,243.
取每行第10个数,计算这3个数的和

第二个数列好像有点问题
:(1)-3,9,-27,81,-243,729.数列为(-1)^n *3^n 3^10
2)0,12,-24,84,-243,729.数列为
3)-1,3,-9,27,-81,243……数列为 (-1)^(n) *3^(n-1) 3^9