VITEEE MATHS Q9

if x^{2}-2xcos\theta +1=0 find the value ofx^{n}(2cosn\theta -x^{n}) where n is a natural number

4 Answers

1
Akshay Pamnani ·

take theta=0
then x=1
so answer is 1

1
Vivek ·

general 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

21
tapanmast Vora ·

Jus put n=1

no need for ne other sub.

U directly get it frm the given eqtn

[4]

1
Vivek ·

u can do that,but thats trial and error,not a solution

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