To simplify the expression $(\sqrt{x+h}) - (\sqrt{x})$, where $x = \sqrt{x}$ and $h \neq 0$, follow these steps:

1. Expression: $(\sqrt{x+h}) - (\sqrt{x})$

2. This expression is already in its simplest form. However, if you're interested in the difference between the square roots, you can rationalize the denominator by multiplying the numerator and the denominator by the conjugate:

$\frac{(\sqrt{x+h}) - (\sqrt{x})}{1} \cdot \frac{(\sqrt{x+h}) + (\sqrt{x})}{(\sqrt{x+h}) + (\sqrt{x})}$

3. Multiply both numerator and denominator:

$\frac{(\sqrt{x+h})^2 - (\sqrt{x})^2}{(\sqrt{x+h}) + (\sqrt{x})}$

4. Simplify the numerator using the difference of squares:

[ \frac{(