Answer
Fill the blank with
$\sqrt{x}$.
Work Step by Step
This is a complex fraction (has a fraction in the numerator).
Our first goal is to eliminate the fraction in the numerator.
If we multiply the numerator with $\sqrt{x}$, the numerator will equal
$\displaystyle \sqrt{x}(\sqrt{x}+\frac{1}{\sqrt{x}})=x+1$
we must also multiply the denominator with $\sqrt{x},$ in order not to change the value of the initial expression.
The whole expression, after multiplying with $\displaystyle \frac{\sqrt{x}}{\sqrt{x}}$ equals $\displaystyle \frac{x+1}{x\sqrt{x}}$
(there is more work to be done - such as rationalizing the denominator, but this expression is simpler - it is not complex any more )
Fill the blank with
$\sqrt{x}$
