有数列{a}，{b}。abn,ban（n是下标）是什么 数列{cn}的前10项的和等于多少则
\u6c42\u89e3\u6570\u5217\u95ee\u9898\uff0c\u8bf7\u7ed9\u51fa\u8fc7\u7a0b\uff0c\u8c22\u8c22\uff019,\u5df2\u77e5\u6570\u5217\uff5ban\uff5d\u662f\u9996\u9879\u4e3a2\uff0c\u516c\u5dee\u4e3a1\u7684\u7b49\u5dee\u6570\u5217\uff0c\u9009\u9879D\u6b63\u786e~\uff01
\u901a\u9879bn=1*2^(n-1)=2^(n-1)\uff0can=2+(n-1)*1=n+1
\u90a3\u4e48a(bn)=\uff08bn\uff09 +1=2^(n-1) +1
\u5219\u53ef\u77e5\u6570\u5217{a(bn)}\u7684\u6bcf\u4e00\u9879\u662f\u7531\u6570\u5217{bn}\u548c\u5e38\u6570\u5217{1}\u7684\u5bf9\u5e94\u5404\u9879\u7684\u548c\u7ec4\u6210
\u6240\u4ee5\uff1a
\u6570\u5217\uff5babn\uff5d\u7684\u524d10\u9879\u7684\u548c\u7b49\u4e8e=1*(1-2^10)/(1-2) +1*10=1023+10=1033
\u5df2\u77e5\u6570\u5217{an}\u3001{bn}\u90fd\u662f\u7b49\u5dee\u6570\u5217\uff0c\u5176\u9996\u9879\u5206\u522b\u662fa1,b1 ,\u4e14a1+b1=5,a1,b1\u90fd\u662f\u6b63\u6574\u6570\uff0c\u5047\u8bbe cn=abn(n\u4e3a\u6b63\u6574\u6570)\uff0c\u5219\u6570\u5217{cn}\u7684\u524d10\u9879\u7684\u548c\u7b49\u4e8e\u591a\u5c11\u6ce8\u660e\uff1a\u6240\u6709\u7684n\u90fd\u662f\u4e0b\u6807\uff0c\u5e76\u4e14abn \u8868\u793a n\u662fb\u7684\u4e0b\u6807\uff0c\u5e76\u4e14bn \u53c8\u662fa\u7684\u4e0b\u6807\u7b54\u6848\u662f85
从题意分析。。ba(n) 是 b[a(n)]的意思。。
ab(n) 是 a[b(n)]的意思。。
具体来说，a(n) = 3 + (n-1)d. b(n) = q^(n-1),
当d为正整数时，a(n)为正整数，
b[a(n)] = q^[a(n) - 1] = q^[2 + (n-1)d],
b[a(n+1)] = q^[a(n+1)-1] = q^[2+nd].
a(n) = (1/2)^(n-2), b(n) = 2n,
a[b(n)] = (1/2)^[b(n)-2] = (1/2)^[2n-2] = a(2n).
a*bn b*an 中间的乘号省略了。 望采纳
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