Math A285
Di↵erential Equations §1.1: Definitions and Terminology
Instructor: Scott Northrup
This study source was downloaded by 100000900706475 from CourseHero.com on
10-07-2025 23:36:20 GMT -05:00
https://www.coursehero.com/file/251466828/11pdf/
, Definition: Di↵erential Equation
An equation containing derivatives of one or more unknown
functions (or dependent variables), with respect to one or more
independent variables, is said to be a di↵erential equation (DE).
We can classify them by type, order, and linearity
I Type. If the equation has derivatives with respect to a single
independent variable, the equation is said to be an ordinary
di↵erential equation (ODE). If the equation involves partial
derivatives of functions of two or more independent variables,
it is called a partial di↵erential equation (PDE).
I Order. The order of a di↵erential equation is the order of
the highest derivative in the equation.
I Linearity. The general form of an ordinary di↵erential
equation is F (x, y , y 0 , . . . , y (n) ) = 0. We say the ODE is
linear if it has the form
an (x)y (n) + an 1y
(n 1)
+ · · · + a1 (x)y 0 + a0 (x)y + g (x) = 0
This study source was downloaded by 100000900706475 from CourseHero.com on
10-07-2025 23:36:20 GMT -05:00
https://www.coursehero.com/file/251466828/11pdf/
Di↵erential Equations §1.1: Definitions and Terminology
Instructor: Scott Northrup
This study source was downloaded by 100000900706475 from CourseHero.com on
10-07-2025 23:36:20 GMT -05:00
https://www.coursehero.com/file/251466828/11pdf/
, Definition: Di↵erential Equation
An equation containing derivatives of one or more unknown
functions (or dependent variables), with respect to one or more
independent variables, is said to be a di↵erential equation (DE).
We can classify them by type, order, and linearity
I Type. If the equation has derivatives with respect to a single
independent variable, the equation is said to be an ordinary
di↵erential equation (ODE). If the equation involves partial
derivatives of functions of two or more independent variables,
it is called a partial di↵erential equation (PDE).
I Order. The order of a di↵erential equation is the order of
the highest derivative in the equation.
I Linearity. The general form of an ordinary di↵erential
equation is F (x, y , y 0 , . . . , y (n) ) = 0. We say the ODE is
linear if it has the form
an (x)y (n) + an 1y
(n 1)
+ · · · + a1 (x)y 0 + a0 (x)y + g (x) = 0
This study source was downloaded by 100000900706475 from CourseHero.com on
10-07-2025 23:36:20 GMT -05:00
https://www.coursehero.com/file/251466828/11pdf/