1u can do that,but thats trial and error,not a solution
if x^{2}-2xcos\theta +1=0 find the value ofx^{n}(2cosn\theta -x^{n}) where n is a natural number
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4 Answers
1general soln of abv eqn is x=e^{i\theta } (-θ is also a soln,it will also work)
substitute in expression u'll get (cosn\theta + isin(n\theta) )(cosn\theta - isin(n\theta) ) = 1
21Jus put n=1
no need for ne other sub.
U directly get it frm the given eqtn
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