If $x+\frac{1}{x}=2$, then which one of the following is the value of

If $x+\frac{1}{x}=2$, then which one of the following is the value of $x^{32}+\frac{1}{x^{32}}$ ?

-1
0
1
2
This question was previously asked in
UPSC CAPF – 2024
The correct answer is 2.
Given the equation $x + \frac{1}{x} = 2$. To find the value of $x$, we can multiply the entire equation by $x$ (assuming $x \neq 0$, which must be true for $1/x$ to be defined).
$x(x + \frac{1}{x}) = 2x$
$x^2 + 1 = 2x$
Rearranging the terms gives a quadratic equation:
$x^2 – 2x + 1 = 0$
This equation is a perfect square trinomial, which can be factored as $(x-1)^2 = 0$.
Solving for $x$, we get $x-1 = 0$, which means $x = 1$.
Now, we need to find the value of the expression $x^{32} + \frac{1}{x^{32}}$.
Substitute $x = 1$ into the expression:
$1^{32} + \frac{1}{1^{32}} = 1 + \frac{1}{1} = 1 + 1 = 2$.
This problem utilizes a common algebraic trick where if $x + \frac{1}{x} = 2$, then $x$ must be 1 (for real values of x). If $x + \frac{1}{x} = -2$, then $x$ must be -1. For other values like $x + \frac{1}{x} = 1$ or $-1$, $x$ would be complex numbers. The property $1^n = 1$ for any integer $n$ is used in the final calculation.