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Z^3=1+i答案是什么,要详细步骤

题目详情
Z^3=1+i 答案是什么,要详细步骤
▼优质解答
答案和解析
设Z=a+bi
(a+bi)(a+bi)(a+bi)
=(a^2+2abi-b^2)(a+bi)
=(a^3-ab^2+3a^2bi-2ab^2-b^3i)
=(a^3-3ab^2)+(3a^2b-b^3)i
a^3-3ab^2=1
3a^2b-b^3=1
设b/a=k
1-3k^2=3k-k^3=1/a^3
k^3-3K2-3k+1=(k+1)(k^2-4k+1)=0
k1=-1
k2=2+3^(1/2)=3.732
k3=2-3^(1/2)=0.268
a1=[1/(1-3k1^2)]^(1/3)=(-1/2)^(1/3)=-0.794,b1=a1k1=0.794
a2=[1/(1-3k2^2)]^(1/3)=-0.291,b2=a2k2=-1.084
a3=[1/(1-3k3^2)]^(1/3)=1.084,b3=a3k3=0.291