If x + 1 x = 3, then the value of x^3 + 1x^3 is:

Answer: Option B

$$\begin{array}{rl}& \sqrt{x}+\frac{1}{\sqrt{x}}=3\\ & x+\frac{1}{x}=7\\ & x^3+\frac{1}{x^3}=7^3-3\times 7\\ & =343-21\\ & =322\end{array}$$