If 1,ω,ω2,....ωn−1 are n,nth roots of unity, then the value of (9−ω)⋅(9−ω2)⋅(9−ω3)...(9−ωn−1) will be
A
9n+18
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B
9n−1
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C
9n−18
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D
9n+1
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Solution
The correct option is B9n−18 Let x=(1)1/n ⇒xn−1=0 or xn−1=(x−1)(x−ω)(x−ω2)....(x−ωn−1) ⇒xn−1x−1=(x−ω)(x−ω2)(x−ω3)...(x−ωn−1) Putting x=9 on both sides, we get (9−ω)(9−ω2)(9−ω3)...(9−ωn−1)=9n−18.