数列2,5,11,20,X,47中则X=?
问题描述:
数列2,5,11,20,X,47中则X=?
答
32
5 - 2 = 3 = 1*3
11 - 5 = 6 = 2*3
20 - 11 = 9 = 3*3
32 - 20 = 12 = 4*3
47 - 32 = 15 = 5*3