(-27)開立方
(-27)開立方
(-27)開立方
高中數學複數
2011-10-02 4:10 pm
回答 (2)
2011-10-02 4:58 pm
✔ 最佳答案
Solx^3=－27
x^3=－27(Cos0+iSin0)
x^3=－27[Cos(2nπ)+iSin(2nπ)]
x=－3[Cos(2nπ/3)+iSin(2nπ/3)]
(1) n=0
x=－3(Cos0+iSin0)=－3
(2) n=1
x=－3[Cos(2π/3)+iSin(2π/3)]=－3(－1/2+√3i/2)=3/2－3i√3/2
(3) n=2
x=－3[Cos(4π/3)+iSin(4π/3)]=－3(－１/2－√3i/2)=3/2+3i√3/2
2011-10-02 9:17 pm
收錄日期: 2021-04-30 16:06:50
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20111002000015KK10243