4.6.30 · HinglishOrdinary Differential Equations

Solving ODEs with Laplace (including discontinuous forcing)

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4.6.30 · Maths › Ordinary Differential Equations


1. Transform aur uski key property

WHY yeh derivatives ko algebra mein badalta hai? Integration by parts karo:

Boundary term par vanish ho jaata hai (decay ki wajah se) aur par deta hai — yahin se initial conditions algebra mein enter hote hain.


2. Recipe (KAISE solve karte hain koi bhi linear ODE)


3. Discontinuous forcing: Heaviside step

Special case : .

Figure — Solving ODEs with Laplace (including discontinuous forcing)

4. Common mistakes (Steel-man + fix)


5. Flashcards

Laplace transform differentiation ko kya bana deta hai?
se multiplication (IC boundary terms ke saath): .
kyun derive karte hain?
Integration by parts; boundary term deta hai, initial conditions inject karta hai.
ko mein kaise likhte hain?
.
(second shifting theorem).
.
ka inverse kya hai?
— delay AUR gate dono.
.
Laplace method ke teen steps kya hain?
ICs ke saath transform karo; ke liye algebraically solve karo; partial fractions + table se invert karo.
aur kyun?
; se.
ka partial fraction kya hai?
.

Recall Feynman: 12-saal ke bachche ko samjhao

Ek moving-equation ko haath se solve karna waisa hai jaise ek uljha hua knot suljhao jab woh abhi bhi hil raha ho. Laplace transform ek photo leta hai jo motion ko ek simple algebra picture mein freeze kar deta hai ("" ki duniya). Picture-land mein, knot ek seedhi line ban jaati hai jise tum normal arithmetic se kaat sakte ho. Jab kaam ho jaata hai, tum use "un-photo" karke ek moving answer mein wapas laate ho. Aur agar koi seconds par switch kare, toh photo ko sirf ek tag milta hai jiska matlab hai "is part ko 2 seconds late shuru karo" — easy!

Concept Map

hard: derivatives tangle

maps t to s domain

apply L

differentiation becomes times s

injects

solve by algebra

split via partial fractions

match standard pairs

read off terms

models switches

handled cleanly by

Linear ODE in time t

Difficulty

Laplace transform L

Algebraic equation in s

Derivative rule sF minus f0

Initial conditions

Y of s

Inverse transform

Solution y of t

Standard pairs table

Heaviside step u a t

Discontinuous forcing