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If ๐œ” is a complex cube root of unity, find the value of (1+๐œ”)โข(1+๐œ”2)โข(1+๐œ”4)โข(1+๐œ”8)

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Question

If `omega` is a complex cube root of unity, find the value of `(1 + omega)(1 + omega^2)(1 + omega^4)(1 + omega^8)`

Sum
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Solution

ω is a complex cube root of unity

∴ ω3 = 1 and 1 + ω + ω2 = 0

Also, 1 + ω2 = -ω, 1 + ω = -ω2 and ω + ω2 = –1

(1 + ω)(1 + ω2)(1 + ω4)(1 + ω8)

= (1 + ω)(1 + ω2)(1 + ω)(1 + ω2)        ...[โˆต ω3 = 1, ∴ ω4 = ω]

= (- ω2) (- ω) (- ω2) (- ω)

= ω6

= (ω3)2

= (1)2  

= 1

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Chapter 3: Complex Numbers - EXERCISE 3.3 [Page 42]

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