1. **State the problem:** Simplify the expression \(\frac{x^2 - 9}{2x^2 - 7x - 15}\).
2. **Recall the formulas and rules:**
- Difference of squares: \(a^2 - b^2 = (a - b)(a + b)\).
- Factor quadratic expressions by finding two numbers that multiply to \(ac\) and add to \(b\) in \(ax^2 + bx + c\).
- Simplify fractions by canceling common factors.
3. **Factor the numerator:**
\[
x^2 - 9 = (x - 3)(x + 3)
\]
4. **Factor the denominator:**
We want to factor \(2x^2 - 7x - 15\).
- Multiply \(a \times c = 2 \times (-15) = -30\).
- Find two numbers that multiply to \(-30\) and add to \(-7\): these are \(-10\) and \(3\).
- Rewrite the middle term:
\[
2x^2 - 10x + 3x - 15
\]
- Group terms:
\[
(2x^2 - 10x) + (3x - 15)
\]
- Factor each group:
\[
2x(x - 5) + 3(x - 5)
\]
- Factor out common binomial:
\[
(2x + 3)(x - 5)
\]
5. **Rewrite the expression with factors:**
\[
\frac{(x - 3)(x + 3)}{(2x + 3)(x - 5)}
\]
6. **Check for common factors:** None of the factors cancel.
7. **Final simplified expression:**
\[
\frac{(x - 3)(x + 3)}{(2x + 3)(x - 5)}
\]
Simplify Rational Expression F47E18
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