If \( x^{2}+\frac{1}{x^{2}}=2 \) then the value of \( x^{256}+\frac{1}{x^{256}} \) is
Step-by-step Solution:
We are given the equation:
\[
x^2 + \frac{1}{x^2} = 2
\]
Step 1: Identifying the Nature of \( x \)
From the identity:
\[
x^2 + \frac{1}{x^2} = 2 \Rightarrow (x - \frac{1}{x})^2 = x^2 - 2 + \frac{1}{x^2}
\]
Setting \( y = x + \frac{1}{x} \), we can express:
\[
y^2 = x^2 + 2 + \frac{1}{x^2}
\]
Substituting \( x^2 + \frac{1}{x^2} = 2 \):
\[
y^2 = 2 + 2 = 4 \Rightarrow y = \pm 2
\]
Thus, \( x + \frac{1}{x} = 2 \) or \( x + \frac{1}{x} = -2 \).
Step 2: Higher Powers of \( x \)
Using the recurrence relation:
\[
x^n + \frac{1}{x^n} = (x^{n-2} + \frac{1}{x^{n-2}})(x^2 + \frac{1}{x^2}) - (x^{n-4} + \frac{1}{x^{n-4}})
\]
Since \( x + \frac{1}{x} = 2 \), we establish the sequence:
\[
x^2 + \frac{1}{x^2} = 2
\]
\[
x^4 + \frac{1}{x^4} = (x^2 + \frac{1}{x^2})^2 - 2 = 2^2 - 2 = 2
\]
Continuing similarly, we observe that:
\[
x^8 + \frac{1}{x^8} = 2
\]
\[
x^{16} + \frac{1}{x^{16}} = 2
\]
\[
x^{32} + \frac{1}{x^{32}} = 2
\]
\[
x^{64} + \frac{1}{x^{64}} = 2
\]
\[
x^{128} + \frac{1}{x^{128}} = 2
\]
\[
x^{256} + \frac{1}{x^{256}} = 2
\]
Final Answer:
\[
\boxed{2}
\]