Let $x$ be a positive real number such that $x - \frac{1}{x} = 3.$  Find $x + \frac{1}{x}.$
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Let $x$ be a positive real number such that $x - \frac{1}{x} = 3.$  Find $x + \frac{1}{x}.$
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
\sqrt{13}
Let $x$ be a positive real number such that $x - \frac{1}{x} = 3.$  Find $x + \frac{1}{x}.$
train