If $x + \frac{1}{x} = 2\cos \alpha $, then ${x^n} + \frac{1}{{{x^n}}}$ is equal to

JEE MATHEMATICS MCQ: COMPLEX NUMBERS

1 Easy

1 of 1

Application +4 | -1

x + \frac{1}{x} = 2\cos \alpha

, then

{x^n} + \frac{1}{{{x^n}}}

is equal to

View answer and explanation

Correct option: D

2\,\,\cos \,\,n\alpha

Option D (

2\,\cos \,n\alpha

) is correct because it is derived by using De Moivre's theorem and simplifying the expression.

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|z|=1

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\left|\sum\limits_{r=1}^n z_r\right|

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\alpha, \beta

\gamma

|\alpha-\beta|

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z \in C

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