计算(1+2)(1+2²)(1+2^4)(1+2^8)(1+2^16)
问题描述:
计算(1+2)(1+2²)(1+2^4)(1+2^8)(1+2^16)
答
(1+2)(1+2²)(1+2^4)(1+2^8)(1+2^16)
= (1-2)(1+2)(1+2²)(1+2^4)(1+2^8)(1+2^16) / (1-2)
= (1-2²)(1+2²)(1+2^4)(1+2^8)(1+2^16) / (-1)
= - (1-2^4)(1+2^4)(1+2^8)(1+2^16)
= - (1-2^8)(1+2^8)(1+2^16)
= - (1-2^16)(1+2^16)
= 2^32 -1
也就是利用平方差公式,先乘以一个(1-2)再除以一个(1-2),使其与原式依旧相等,然后就可以利用平方差公式计算
答
(1+2)(1+2²)(1+2^4)(1+2^8)(1+2^16)= (1-2)(1+2)(1+2²)(1+2^4)(1+2^8)(1+2^16) / (1-2)= (1-2²)(1+2²)(1+2^4)(1+2^8)(1+2^16) / (-1)= - (1-2^4)(1+2^4)(1+2^8)(1+2^16)= - (1-2^8)(1+2^8)(1+2^...