1. **State the problem:** Find a polynomial function of degree 4 with zeros at $-2$ and $2$, each with multiplicity 2, and whose graph passes through the point $(-4, 432)$.
2. **Write the general form:** Since the zeros are $-2$ and $2$ with multiplicity 2, the polynomial can be written as:
$$f(x) = a(x + 2)^2 (x - 2)^2$$
where $a$ is a constant to be determined.
3. **Use the given point to find $a$:** Substitute $x = -4$ and $f(x) = 432$:
$$432 = a(-4 + 2)^2 (-4 - 2)^2$$
Calculate inside the parentheses:
$$432 = a(-2)^2 (-6)^2$$
Simplify powers:
$$432 = a(4)(36)$$
$$432 = 144a$$
Divide both sides by 144:
$$\cancel{144}a = \frac{432}{\cancel{144}}$$
$$a = 3$$
4. **Write the final polynomial:**
$$f(x) = 3(x + 2)^2 (x - 2)^2$$
5. **Optional expansion:**
$$(x + 2)^2 = x^2 + 4x + 4$$
$$(x - 2)^2 = x^2 - 4x + 4$$
Multiply:
$$(x^2 + 4x + 4)(x^2 - 4x + 4) = x^4 - 4x^3 + 4x^2 + 4x^3 - 16x^2 + 16x + 4x^2 - 16x + 16$$
Simplify:
$$x^4 + ( -4x^3 + 4x^3 ) + (4x^2 - 16x^2 + 4x^2) + (16x - 16x) + 16 = x^4 - 8x^2 + 16$$
Multiply by 3:
$$f(x) = 3x^4 - 24x^2 + 48$$
**Final answer in factored form:**
$$f(x) = 3(x + 2)^2 (x - 2)^2$$
Degree 4 Polynomial 58D275
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