Limit Rationalization
1. **State the problem:** Find the limit $$\lim_{x \to 3} \frac{2x - 6}{\sqrt{x+1} - 2}$$.
2. **Identify the indeterminate form:** Substitute $x=3$ directly:
$$\frac{2(3) - 6}{\sqrt{3+1} - 2} = \frac{6 - 6}{2 - 2} = \frac{0}{0}$$ which is indeterminate.
3. **Rationalize the denominator:** Multiply numerator and denominator by the conjugate of the denominator:
$$\frac{2x - 6}{\sqrt{x+1} - 2} \times \frac{\sqrt{x+1} + 2}{\sqrt{x+1} + 2} = \frac{(2x - 6)(\sqrt{x+1} + 2)}{(\sqrt{x+1} - 2)(\sqrt{x+1} + 2)}$$
4. **Simplify the denominator using difference of squares:**
$$ (\sqrt{x+1})^2 - 2^2 = (x+1) - 4 = x - 3 $$
5. **Rewrite the expression:**
$$ \frac{(2x - 6)(\sqrt{x+1} + 2)}{x - 3} $$
6. **Factor numerator term:**
$$ 2x - 6 = 2(x - 3) $$
7. **Cancel common factor $(x-3)$:**
$$ \frac{2(x - 3)(\sqrt{x+1} + 2)}{x - 3} = 2(\sqrt{x+1} + 2) $$
8. **Evaluate the limit by substituting $x=3$:**
$$ 2(\sqrt{3+1} + 2) = 2(2 + 2) = 2 \times 4 = 8 $$
**Final answer:** 8