1. The problem asks for the residue of the function $$f(z) = \frac{1}{(z-2)(z+2)(z-3)}$$ at the point $$z_0 = 3$$.
2. The residue at a simple pole $$z_0$$ of a function $$f(z) = \frac{g(z)}{h(z)}$$ where $$h(z_0) = 0$$ and $$h'(z_0) \neq 0$$ is given by:
$$\text{Res}(f, z_0) = \frac{g(z_0)}{h'(z_0)}$$
3. Here, rewrite $$f(z)$$ as:
$$f(z) = \frac{1}{(z-3)(z-2)(z+2)}$$
4. Define:
$$g(z) = 1$$
$$h(z) = (z-3)(z-2)(z+2)$$
5. Compute the derivative $$h'(z)$$ using the product rule:
$$h'(z) = \frac{d}{dz}[(z-3)(z-2)(z+2)]$$
6. First, expand partially or use product rule stepwise:
$$h'(z) = (z-2)(z+2) + (z-3)(z+2) + (z-3)(z-2)$$
7. Evaluate each term at $$z=3$$:
- $$(3-2)(3+2) = 1 \times 5 = 5$$
- $$(3-3)(3+2) = 0 \times 5 = 0$$
- $$(3-3)(3-2) = 0 \times 1 = 0$$
8. Sum these values:
$$h'(3) = 5 + 0 + 0 = 5$$
9. Calculate the residue:
$$\text{Res}(f, 3) = \frac{g(3)}{h'(3)} = \frac{1}{5}$$
10. Now, identify which function among the options matches the original function:
- Option a: $$\frac{1}{z^2 + 4}$$
- Option b: $$\frac{1}{z^2 + 4z - 6}$$
- Option c: $$\frac{1}{z^2 - 4}$$
- Option d: $$\frac{1}{z^2 + 4z + 6}$$
11. The original denominator is:
$$(z-2)(z+2)(z-3) = (z^2 - 4)(z-3) = z^3 - 3z^2 - 4z + 12$$
12. None of the options match the full denominator, but the question likely asks which function corresponds to the factorization related to the poles.
13. The factor $$z^2 - 4$$ corresponds to $$(z-2)(z+2)$$, which is option c.
14. Therefore, the function $$f(z) = \frac{1}{(z-2)(z+2)(z-3)}$$ contains the factor $$\frac{1}{z^2 - 4}$$ as part of its denominator.
Final answer: Option c: $$f(z) = \frac{1}{z^2 - 4}$$
Residue At 3 Dc3B29
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