设：x1 = ax2 = aaxn = aaaaa.a(n个)观察可得：x(n+1) = 10xn + a等式两边同时加 a/9得：x(n+1) + a/9 = 10xn + 10a/9即：x(n+1) + a/9 = 10(xn + a/9)这样我们可以知道（xn + a/9）是一个等比数列.首项10a/9,公比10...