Inverse Laplace
1. **State the problem:** Find the inverse Laplace transform of the function $$F(s) = \frac{2s - 3}{s^2 - 4}$$.
2. **Factor the denominator:** Note that $$s^2 - 4 = (s - 2)(s + 2)$$.
3. **Partial fraction decomposition:** Express $$F(s)$$ as
$$\frac{2s - 3}{(s - 2)(s + 2)} = \frac{A}{s - 2} + \frac{B}{s + 2}$$
Multiply both sides by $$ (s - 2)(s + 2) $$:
$$2s - 3 = A(s + 2) + B(s - 2)$$
4. **Find coefficients A and B:**
Set $$s = 2$$:
$$2(2) - 3 = A(2 + 2) + B(0) \Rightarrow 4 - 3 = 4A \Rightarrow 1 = 4A \Rightarrow A = \frac{1}{4}$$
Set $$s = -2$$:
$$2(-2) - 3 = A(0) + B(-2 - 2) \Rightarrow -4 - 3 = -4B \Rightarrow -7 = -4B \Rightarrow B = \frac{7}{4}$$
5. **Rewrite the function:**
$$F(s) = \frac{1/4}{s - 2} + \frac{7/4}{s + 2}$$
6. **Recall inverse Laplace transforms:**
$$\mathcal{L}^{-1}\left\{ \frac{1}{s - a} \right\} = e^{at}$$
7. **Apply inverse Laplace transform:**
$$f(t) = \frac{1}{4}e^{2t} + \frac{7}{4}e^{-2t}$$
**Final answer:**
$$\boxed{f(t) = \frac{1}{4}e^{2t} + \frac{7}{4}e^{-2t}}$$