Rational Expression Simplify 21F7Bc
1. **State the problem:** Simplify the expression
$$\frac{16x^2 + 24x + 9}{3x^2 + 13x - 10} \cdot \frac{6x^2 + 25x - 25}{4x^2 - 13x - 12}$$
and verify the factorization
$$(4x + 3)(4x + 3) \cdot (x + 5)(x + 5)$$
2. **Factor each polynomial:**
- Numerator 1: $16x^2 + 24x + 9 = (4x + 3)^2$
- Denominator 1: $3x^2 + 13x - 10$
Find factors of $3 \times (-10) = -30$ that sum to 13: 15 and -2
So,
$$3x^2 + 15x - 2x - 10 = 3x(x + 5) - 2(x + 5) = (3x - 2)(x + 5)$$
- Numerator 2: $6x^2 + 25x - 25$
Factors of $6 \times (-25) = -150$ that sum to 25: 30 and -5
So,
$$6x^2 + 30x - 5x - 25 = 6x(x + 5) - 5(x + 5) = (6x - 5)(x + 5)$$
- Denominator 2: $4x^2 - 13x - 12$
Factors of $4 \times (-12) = -48$ that sum to -13: -16 and 3
So,
$$4x^2 - 16x + 3x - 12 = 4x(x - 4) + 3(x - 4) = (4x + 3)(x - 4)$$
3. **Rewrite the expression with factors:**
$$\frac{(4x + 3)^2}{(3x - 2)(x + 5)} \cdot \frac{(6x - 5)(x + 5)}{(4x + 3)(x - 4)}$$
4. **Simplify by canceling common factors:**
- Cancel one $(4x + 3)$ from numerator and denominator
- Cancel $(x + 5)$ from numerator and denominator
Resulting expression:
$$\frac{4x + 3}{3x - 2} \cdot \frac{6x - 5}{x - 4} = \frac{(4x + 3)(6x - 5)}{(3x - 2)(x - 4)}$$
5. **Multiply the numerators and denominators:**
Numerator:
$$ (4x + 3)(6x - 5) = 24x^2 - 20x + 18x - 15 = 24x^2 - 2x - 15$$
Denominator:
$$ (3x - 2)(x - 4) = 3x^2 - 12x - 2x + 8 = 3x^2 - 14x + 8$$
6. **Final simplified expression:**
$$\frac{24x^2 - 2x - 15}{3x^2 - 14x + 8}$$
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**Verification of given factorization:**
$$(4x + 3)(4x + 3) \cdot (x + 5)(x + 5) = (4x + 3)^2 (x + 5)^2$$
This matches the factorization of the numerators combined.
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**Answer:**
$$\boxed{\frac{24x^2 - 2x - 15}{3x^2 - 14x + 8}}$$