Simplify Rational Expression D0536D
1. **State the problem:** Simplify the expression $\frac{x^2 - 9}{5x^2 - 11x - 12}$.
2. **Factor numerator and denominator:**
- Numerator: $x^2 - 9$ is a difference of squares, so $x^2 - 9 = (x - 3)(x + 3)$.
- Denominator: Factor $5x^2 - 11x - 12$.
3. **Factor denominator:**
We look for two numbers that multiply to $5 \times (-12) = -60$ and add to $-11$.
These numbers are $-15$ and $4$.
Rewrite middle term:
$$5x^2 - 15x + 4x - 12$$
Group terms:
$$(5x^2 - 15x) + (4x - 12)$$
Factor each group:
$$5x(x - 3) + 4(x - 3)$$
Factor out common binomial:
$$(5x + 4)(x - 3)$$
4. **Rewrite the expression:**
$$\frac{(x - 3)(x + 3)}{(5x + 4)(x - 3)}$$
5. **Cancel common factors:**
Since $x - 3$ appears in numerator and denominator (and $x \neq 3$ to avoid division by zero), cancel it:
$$\frac{x + 3}{5x + 4}$$
6. **Final answer:**
$$\boxed{\frac{x + 3}{5x + 4}}$$
This is the simplified form of the original expression.