1. **State the problem:** Find the extrema (maximum and minimum points) of the function $$f(x) = (x-2)(x+3)^2(x+7)$$.
2. **Formula and rules:** To find extrema, we need to find critical points where the derivative $$f'(x)$$ is zero or undefined. Then, use the first or second derivative test to classify these points.
3. **Find the derivative:** Use the product rule and chain rule.
Let $$u = (x-2), v = (x+3)^2, w = (x+7)$$.
Then $$f(x) = u \cdot v \cdot w$$.
Derivative:
$$f'(x) = u'vw + uv'w + uvw'$$
Calculate each:
- $$u' = 1$$
- $$v' = 2(x+3)$$
- $$w' = 1$$
So,
$$f'(x) = 1 \cdot (x+3)^2 \cdot (x+7) + (x-2) \cdot 2(x+3) \cdot (x+7) + (x-2)(x+3)^2 \cdot 1$$
4. **Simplify:**
$$f'(x) = (x+3)^2 (x+7) + 2(x-2)(x+3)(x+7) + (x-2)(x+3)^2$$
Factor common terms:
All terms have at least one $(x+3)$ and $(x-2)$ or $(x+7)$, but let's factor stepwise.
Rewrite:
$$f'(x) = (x+3)^2 (x+7) + 2(x-2)(x+3)(x+7) + (x-2)(x+3)^2$$
Group terms:
$$= (x+3)^2 (x+7) + (x-2)(x+3)^2 + 2(x-2)(x+3)(x+7)$$
Factor $(x+3)$ from the last two terms:
$$= (x+3)^2 (x+7) + (x-2)(x+3)[(x+3) + 2(x+7)]$$
Simplify inside bracket:
$$(x+3) + 2(x+7) = x+3 + 2x +14 = 3x +17$$
So,
$$f'(x) = (x+3)^2 (x+7) + (x-2)(x+3)(3x +17)$$
Factor $(x+3)$:
$$f'(x) = (x+3)[(x+3)(x+7) + (x-2)(3x +17)]$$
Expand inside bracket:
$$(x+3)(x+7) = x^2 + 10x + 21$$
$$(x-2)(3x +17) = 3x^2 +17x -6x -34 = 3x^2 +11x -34$$
Sum:
$$x^2 + 10x + 21 + 3x^2 + 11x -34 = 4x^2 + 21x -13$$
So,
$$f'(x) = (x+3)(4x^2 + 21x -13)$$
5. **Find critical points:** Set $$f'(x) = 0$$
$$ (x+3)(4x^2 + 21x -13) = 0 $$
So,
$$x = -3$$ or solve quadratic:
$$4x^2 + 21x -13 = 0$$
Use quadratic formula:
$$x = \frac{-21 \pm \sqrt{21^2 - 4 \cdot 4 \cdot (-13)}}{2 \cdot 4} = \frac{-21 \pm \sqrt{441 + 208}}{8} = \frac{-21 \pm \sqrt{649}}{8}$$
6. **Classify critical points:** Use second derivative or test values around points.
Final extrema points are at:
$$x = -3, \quad x = \frac{-21 + \sqrt{649}}{8}, \quad x = \frac{-21 - \sqrt{649}}{8}$$
Extrema Finding E93168
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.