1. **Problem (a):** Given that $f(x) = (x - a)^2 g(x)$, where $f(x)$ and $g(x)$ are polynomials, show that $(x - a)$ is a factor of $f'(x)$.
2. **Step 1:** Differentiate $f(x)$ using the product rule:
$$f'(x) = \frac{d}{dx}[(x - a)^2 g(x)] = 2(x - a) g(x) + (x - a)^2 g'(x)$$
3. **Step 2:** Factor out $(x - a)$ from $f'(x)$:
$$f'(x) = (x - a) \left[ 2 g(x) + (x - a) g'(x) \right]$$
4. Since $2 g(x) + (x - a) g'(x)$ is a polynomial, $(x - a)$ is a factor of $f'(x)$.
---
5. **Problem (b):** Given that $(x - 3)^2$ is a factor of $2x^3 - 4x^2 + p x + q$, find $p$ and $q$.
6. **Step 1:** Since $(x - 3)^2$ is a factor, the polynomial and its derivative must both be zero at $x=3$.
7. **Step 2:** Evaluate the polynomial at $x=3$:
$$2(3)^3 - 4(3)^2 + p(3) + q = 0$$
$$2 \times 27 - 4 \times 9 + 3p + q = 0$$
$$54 - 36 + 3p + q = 0$$
$$18 + 3p + q = 0 \implies 3p + q = -18$$
8. **Step 3:** Differentiate the polynomial:
$$f'(x) = 6x^2 - 8x + p$$
9. **Step 4:** Evaluate $f'(x)$ at $x=3$:
$$6(3)^2 - 8(3) + p = 0$$
$$6 \times 9 - 24 + p = 0$$
$$54 - 24 + p = 0$$
$$30 + p = 0 \implies p = -30$$
10. **Step 5:** Substitute $p = -30$ into $3p + q = -18$:
$$3(-30) + q = -18$$
$$-90 + q = -18$$
$$q = 72$$
**Final answers:**
$$p = -30, \quad q = 72$$
Factor Derivative
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.