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if 1,ω,ω² are three cube roots of unity, prove that (1+5ω²+ω⁴)(1+5ω+ω²)(5+ω+ω²)=64 |
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Answer» Formulas to be used: 1) 1+ω+ω2=0 2) ω3k=1,ω3k+1=ω,ω3k+2=ω2 So,(1+5ω²+ω⁴)(1+5ω+ω²)(5+ω+ω²) (1+5ω2+ω)(1+5ω+ω2)(5+ω+ω2) So, 1+ω=-ω2,1+ω2=-ω, ω+ω2=-1 (5ω2-ω2)(5ω-ω)(5-1) (4ω2)(4ω)(4) 64ω3=64 Hence Proved (1 + 5ω2 + ω4) (1 + 5ω + ω2) ( 5 + ω + ω2) = (1 + ω + ω2 + 4ω2) ( 1 + ω + ω2 + 4ω) ( 4 +1 + ω + ω2) (∵ ω3 = 1 ⇒ ω4 = ω) = 4ω2.4ω.4 (∵ 1 + ω + ω2 = 0) = 64ω3 = 64 (∵ ω3 = 1) |
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