Question

学霸！这道数学题怎么做？

Answer 1

n为正整数

追问

怎么得出这个？

追答

稍等，我的方法比较笨，我整理下过程给你图片。

Answer 2

追问

为什么是四的n-2次方 而不是四的n-1次方？

还有一点就是你为什么懂减少三分之二而不是别的？

追答

因为n≥2呀。
因为b(n-1)前的系数是4，所以假设bn是等比数列，再凑数看能不能真的构成一个等比，最后得到-2/3。

Answer 3

A(n)=2n-1→A(B(n-1))=2B(n-1)-1
Bn=2A(B(n-1))=2(2B(n-1)-1)=4B(n-1)-2
前面应该是构成了数列An吧

追问

这个还不是最简的吧？

Answer 4

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