这题关键是利用欧拉公式,e^(iθ)=cosθ+isinθ
1+i=(根号2)*[(cos(π/4)+isin(π/4)]=(根号2)*e^(i*π/4)
(1+i)^100=(根号2)^100*e(i*25π)=2^50*(cos25π+isin25π)
=-2^50
同理(1-i)^100=-2^50
(1+i)^100+(1-i)^100=-2^50-2^50=-2^51
答案为什么是正的2^51
呢,是不是看错了
将式子化为e形式
原式=e∧{(1+i)Ln2}
=e∧{(Ln2)+Ln2i}
=e∧(ln2) X e∧{(ln2i)+i(argtan0+2kπi)}
argtan0=0
原式就=2e∧{i(ln2)-2kπ} k=0,±1,±2......
2^(1+i)
=[e^(ln2+2kπi)]^(1+i) (k∈Z)
=e^[(ln2+2kπi)·(1+i)]
=e^[ln2-2kπ+(2kπ+ln2)i]
=2·e^(-2kπ)·[cos(2kπ+ln2)+isin(2kπ+ln2)]
=2·e^(-2kπ)·[cos(ln2)+isin(ln2)]
(k∈Z)