Logarithmic Inequality A3E48F
1. **State the problem:** Solve the inequality $$\ln(x-1) + \ln(x-3) > \ln(3)$$ for $x$.
2. **Use logarithm properties:** Recall that $$\ln(a) + \ln(b) = \ln(ab)$$ for $a,b>0$.
3. **Rewrite the inequality:**
$$\ln((x-1)(x-3)) > \ln(3)$$
4. **Exponentiate both sides:** Since the natural logarithm function is increasing, the inequality holds if and only if
$$(x-1)(x-3) > 3$$
5. **Expand and simplify:**
$$(x-1)(x-3) = x^2 - 4x + 3$$
So the inequality becomes
$$x^2 - 4x + 3 > 3$$
6. **Subtract 3 from both sides:**
$$x^2 - 4x + 3 - 3 > 0 \implies x^2 - 4x > 0$$
7. **Factor the quadratic:**
$$x(x - 4) > 0$$
8. **Analyze the inequality:** The product $x(x-4)$ is positive when both factors are positive or both are negative.
- Case 1: $x > 0$ and $x - 4 > 0 \implies x > 4$
- Case 2: $x < 0$ and $x - 4 < 0 \implies x < 0$
9. **Consider domain restrictions:** The original logarithms require
$$x - 1 > 0 \implies x > 1$$
$$x - 3 > 0 \implies x > 3$$
So the domain is $x > 3$.
10. **Combine domain and solution:** From the domain $x > 3$ and the solution intervals, only $x > 4$ satisfies both.
**Final answer:**
$$\boxed{x > 4}$$