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Find the 8th roots of 3i-3
Urgent...please help!!!!

User Blayne
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1 Answer

2 votes

z=-3+3i=3(-1+i)=3\left(\sqrt2e^(i3\pi/4)\right)=3\sqrt2e^(i3\pi/4)

Let
z=w^8. Then the eight roots of
z are


w=\left(3\sqrt2e^(i3\pi/4)\right)^(1/8)

w=3^(1/8)2^(1/16)}e^(i(3\pi/4+2\pi k)/8)

where
k=0,1,\ldots,7. So the eighth roots are


w=\begin{cases}3^(1/8)2^(1/16)e^(i3\pi/32)&\text{for }k=0\\\\3^(1/8)2^(1/16)e^(i11\pi/32)&\text{for }k=1\\\\3^(1/8)2^(1/16)e^(i19\pi/32)&\text{for }k=2\\\\3^(1/8)2^(1/16)e^(i27\pi/32)&\text{for }k=3\\\\3^(1/8)2^(1/16)e^(i35\pi/32)&\text{for }k=4\\\\3^(1/8)2^(1/16)e^(i43\pi/32)&\text{for }k=5\\\\3^(1/8)2^(1/16)e^(i51\pi/32)&\text{for }k=6\\\\3^(1/8)2^(1/16)e^(i59\pi/32)&\text{for }k=7\end{cases}
User Moshisho
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