
问一道复数的选择题第5题
2个回答
展开全部
x=(-1/2)+(√3/2)i=cos(2π/3)+isin(2π/3)
y=(-1/2)-(√3/2)i=cos(4π/3)+isin(4π/3)
所以:x^5+y^5
=cos(10π/3)+isin(10π/3)+cos(20π/3)+isin(20π/3)
=cos(-2π/3)+isin(-2π/3)+cos(2π/3)+isin(2π/3)
=-1
其余的都这样进行检验!
y=(-1/2)-(√3/2)i=cos(4π/3)+isin(4π/3)
所以:x^5+y^5
=cos(10π/3)+isin(10π/3)+cos(20π/3)+isin(20π/3)
=cos(-2π/3)+isin(-2π/3)+cos(2π/3)+isin(2π/3)
=-1
其余的都这样进行检验!
追问
这个题没有简单做法吗?
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