If x - 1 x = 5 , then x^2 + 1x^2 is equal to:

Answer: Option C

$$\begin{array}{rl}& \sqrt{x}-\frac{1}{\sqrt{x}}=\sqrt{5}\\ & \text{Square both side}\\ & x+\frac{1}{x}-2.x.\frac{1}{x}=5\\ & x+\frac{1}{x}=5+2\\ & \text{Square both side}\\ & x^2+\frac{1}{x^2}+2.x.\frac{1}{x}=49\\ & x^2+\frac{1}{x^2}=47\end{array}$$