If $x^4 + x^{-4} = 194$, x > 0, then the value of $x +\frac{1}{x}$ is:

14 6 4 8

4

If x4 + \(\frac{1}{x^4}\) = a then x2 + \(\frac{1}{x^2}\) = \(\sqrt {a + 2}\) = b and x + \(\frac{1}{x}\) = \(\sqrt {b + 2}\) If $x^4 + x^{-4} = 194$ then x2 + \(\frac{1}{x^2}\) = \(\sqrt {194 + 2}\) = 14 and x + \(\frac{1}{x}\) = \(\sqrt {14 + 2}\) = 4