Question: Which equation is set up for direct use of the zero-factor property? Solve it.
A. $7x^2 - 32x - 15 = 0$ B. $(2x + 5)^2 = 3$
C. $x^2 + x = 20$ D. $(7x - 3)(x - 7) = 0$
Choose the correct answer below.
A. $7x^2 - 32x - 15 = 0$
B. $(2x + 5)^2 = 3$
C. $x^2 + x = 20$
D. $(7x - 3)(x - 7) = 0$
1. **State the problem:** We need to identify which equation is already set up for direct use of the zero-factor property and then solve it.
2. **Recall the zero-factor property:** If a product of factors equals zero, then at least one of the factors must be zero. Formally, if $$A \cdot B = 0$$ then $$A = 0$$ or $$B = 0$$.
3. **Analyze each option:**
- A. $7x^2 - 32x - 15 = 0$ is a quadratic equation but not factored.
- B. $(2x + 5)^2 = 3$ is not equal to zero, so zero-factor property does not apply directly.
- C. $x^2 + x = 20$ is not factored and not equal to zero.
- D. $(7x - 3)(x - 7) = 0$ is factored and equal to zero, so zero-factor property applies directly.
4. **Choose option D and solve:**
Set each factor equal to zero:
$$7x - 3 = 0$$
$$x - 7 = 0$$
5. **Solve each equation:**
For $$7x - 3 = 0$$:
$$7x = 3$$
$$x = \frac{3}{7}$$
For $$x - 7 = 0$$:
$$x = 7$$
6. **Final answer:** The solutions are $$x = \frac{3}{7}$$ and $$x = 7$$.
Thus, the equation set up for direct use of the zero-factor property is option D: $(7x - 3)(x - 7) = 0$ and its solutions are $x = \frac{3}{7}$ and $x = 7$.