Question: Rationalize the denominator of $\frac{\sqrt{g}}{\sqrt{g} + \sqrt{k}}$. Assume that all variables represent positive real numbers.
1. **State the problem:** Rationalize the denominator of the expression $$\frac{\sqrt{g}}{\sqrt{g} + \sqrt{k}}$$ where $g$ and $k$ are positive real numbers.
2. **Recall the formula:** To rationalize a denominator of the form $a + b$, multiply numerator and denominator by the conjugate $a - b$ to use the difference of squares formula: $$(a + b)(a - b) = a^2 - b^2$$
3. **Apply the conjugate:** Multiply numerator and denominator by $$\sqrt{g} - \sqrt{k}$$:
$$\frac{\sqrt{g}}{\sqrt{g} + \sqrt{k}} \times \frac{\sqrt{g} - \sqrt{k}}{\sqrt{g} - \sqrt{k}} = \frac{\sqrt{g}(\sqrt{g} - \sqrt{k})}{(\sqrt{g} + \sqrt{k})(\sqrt{g} - \sqrt{k})}$$
4. **Simplify numerator:**
$$\sqrt{g} \times \sqrt{g} - \sqrt{g} \times \sqrt{k} = g - \sqrt{g}\sqrt{k}$$
5. **Simplify denominator using difference of squares:**
$$(\sqrt{g})^2 - (\sqrt{k})^2 = g - k$$
6. **Write the expression:**
$$\frac{g - \sqrt{g}\sqrt{k}}{g - k}$$
7. **Final answer:**
$$\frac{g - \sqrt{g}\sqrt{k}}{g - k}$$
This is the rationalized form of the original expression.