Rational Expression Simplify 1C5D9D
1. **State the problem:** Simplify the expression $$\frac{x + 7}{x + 5} - \frac{7x}{x^2 - 3x - 40}$$ to a single simplified fraction.
2. **Factor the denominator:** The second denominator is a quadratic. Factor it:
$$x^2 - 3x - 40 = (x - 8)(x + 5)$$
3. **Rewrite the expression with factored denominators:**
$$\frac{x + 7}{x + 5} - \frac{7x}{(x - 8)(x + 5)}$$
4. **Find the common denominator:** The least common denominator (LCD) is $$ (x + 5)(x - 8) $$.
5. **Rewrite each fraction with the LCD:**
- First fraction: multiply numerator and denominator by $$ (x - 8) $$
$$\frac{(x + 7)(x - 8)}{(x + 5)(x - 8)}$$
- Second fraction already has the LCD.
6. **Combine the fractions:**
$$\frac{(x + 7)(x - 8) - 7x}{(x + 5)(x - 8)}$$
7. **Expand the numerator:**
$$ (x + 7)(x - 8) = x^2 - 8x + 7x - 56 = x^2 - x - 56 $$
8. **Subtract $$7x$$:**
$$ x^2 - x - 56 - 7x = x^2 - 8x - 56 $$
9. **Simplify numerator:**
$$ x^2 - 8x - 56 $$
10. **Factor numerator if possible:**
$$ x^2 - 8x - 56 = (x - 14)(x + 4) $$
11. **Write the final simplified expression:**
$$\frac{(x - 14)(x + 4)}{(x + 5)(x - 8)}$$
**Answer:** $$\frac{(x - 14)(x + 4)}{(x + 5)(x - 8)}$$