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Laplace Transform Formulae
Laplace Transform Formulae

🧮 Laplace Transform Basics

\[ \mathcal{L}\{f(t)\} = F(s), \quad F(s) = \int_0^{\infty} e^{-st} f(t)\, dt \]

📘 Common Laplace Transforms

Function \( f(t) \) Laplace Transform \( F(s) \)
\( 1 \)\( \frac{1}{s}, \quad \text{Re}(s) > 0 \)
\( t \)\( \frac{1}{s^2} \)
\( t^n \)\( \frac{n!}{s^{n+1}} \)
\( e^{at} \)\( \frac{1}{s - a} \)
\( \sin(at) \)\( \frac{a}{s^2 + a^2} \)
\( \cos(at) \)\( \frac{s}{s^2 + a^2} \)
\( \sinh(at) \)\( \frac{a}{s^2 - a^2} \)
\( \cosh(at) \)\( \frac{s}{s^2 - a^2} \)
\( u_c(t) \)\( \frac{e^{-cs}}{s} \)
\( \delta(t - a) \)\( e^{-as} \)

🔁 Shifting Theorems

Time Shifting:

\[ \mathcal{L}\{f(t - a)u(t - a)\} = e^{-as}F(s) \]

Frequency Shifting:

\[ \mathcal{L}\{e^{at}f(t)\} = F(s - a) \]

🧠 Derivatives and Integrals

First Derivative:

\[ \mathcal{L}\{f'(t)\} = sF(s) - f(0) \]

Second Derivative:

\[ \mathcal{L}\{f''(t)\} = s^2F(s) - sf(0) - f'(0) \]

n-th Derivative:

\[ \mathcal{L}\{f^{(n)}(t)\} = s^nF(s) - s^{n-1}f(0) - \dots - f^{(n-1)}(0) \]

Integration:

\[ \mathcal{L}\left\{\int_0^t f(\tau)\,d\tau\right\} = \frac{F(s)}{s} \]

🔧 Other Properties

Linearity:

\[ \mathcal{L}\{a f(t) + b g(t)\} = a F(s) + b G(s) \]

Convolution:

\[ \mathcal{L}\{f(t) * g(t)\} = F(s)G(s) \]

Initial Value Theorem:

\[ \lim_{t \to 0^+} f(t) = \lim_{s \to \infty} sF(s) \]

Final Value Theorem:

\[ \lim_{t \to \infty} f(t) = \lim_{s \to 0} sF(s), \quad \text{if limit exists} \]