Math 330: Ordinary Differential Equations
October 18, 2025
Direction fields for first order equations
Autonomous equations; equilibrium solutions; asymptotically stable, unstable and semi-stable solutions
First order equations; initial value problems
First order linear equations; the method of integrating factor
First order linear equations; the method of variation of parameter
Separable equations
Applications: compound interest, population growth, radioactive decay, solution mixing, Newton's Law of cooling
Existence and uniqueness theorem for first order linear equations
Existence and uniqueness theorem for non-linear first order equations
Bernoulli equation
Logistic model of population growth; carrying capacity
Exact equations
Euler’s numerical method for first order equations
Picard’s method of successive approximations
Second order linear differential equations; initial value problems; homogeneous and non-homogeneous equations
Existence and uniqueness theorem for second-order linear differential equations (Theorem 3.2.1)
The superposition principle (Theorem 3.2.2)
Second-order linear homogeneous equations with constant coefficients; characteristic equation
Case of two distinct real roots of characteristic equation
Linear differential operator notation
Wronski determinant (Wronskian)
Theorems about constants (TACO) (Theorem 3.2.3) and about the general solution (TAGS) (Theorem 3.2.4); fundamental set of solutions
Abel’s theorem (AT) (Theorem 3.2.7)
Case of complex roots of characteristic equation; Euler’s formula; obtaining real-valued solutions
Case of repeated roots of characteristic equation; method of reduction of order
Non-homogeneous second order linear differential equations; DIFIFI Theorem (Theorem 3.5.1) and Theorem about the general solution of a non-homogeneous linear equation (Theorem 3.5.2)
Solving non-homogeneous equations; finding particular solutions using method of similarity (MOS) and method of undetermined coefficients (MOUC); both in straightforward cases as well as cases with conflict(s) between the homogeneous equation's solution and the function g(t)
Solving non-homogeneous equations with the method of variation of parameters