If X - 1/x = 13, what will be the value of X^4 +1/(x^4)?

If $X - \frac{1}{x} = 13$

Then ,

x + \(\frac{1}{x}\) = \(\sqrt {13^2 + 4}\) =  \(\sqrt {173}\)

then x² + \(\frac{1}{x^2}\) = (\(\sqrt {173}\))² - 2 = 171

and x⁴ + \(\frac{1}{x^4}\) = 171² - 2 = 29239