Section 24.1

Basic Concepts for n-th Order

Extending the theory from 2nd order to n-th order. Most properties generalize naturally.

1

Introduction

An -th order linear DE looks like:

We need initial conditions: .

2

Existence & Uniqueness

Theorem

If all and are continuous on an interval containing , then there exists a unique solution on .

3

Linear Independence

A set of functions is linearly independent if implies all .

The Wronskian is now an determinant of the functions and their derivatives up to .

4

Worked Examples

Example 1: Wronskian

Check if are independent.

Determinant of triangulation matrix = product of diagonal.

.

They are independent.

Example 2: Interval of Existence

with .

Standard form: .

Discontinuities at .

requires .

Initial condition at is in .

Unique solution exists on .

Example 3: Visual Basis

A fundamental set of solutions forms a "basis" for the solution space.

5

Practice Quiz

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