# I First order differential equations ??

1. Jul 23, 2016

### awholenumber

what is a good book to learn first order differential equations ??

2. Jul 23, 2016

### BvU

There's a forum dedicated to this.

3. Jul 23, 2016

### awholenumber

BvU ,

thanks a lot ...

i was getting lost in the classifications and complexities of these differential equations ...

4. Jul 23, 2016

### BvU

Take it easy: all beginnings are somewhat bewildering...

5. Jul 23, 2016

### awholenumber

BvU ,

thanks ...

i saw this image while i was googling for first order differential equations ...

does all these belong to only first order differential equations ??

separable equations
homogeneous equations
linear equations
exact equations

or is it like ...

separable equations with only first derivatives
homogeneous equations with only first derivatives
linear equations with only first derivatives
exact equations with only first derivatives

??

6. Jul 23, 2016

### BvU

The latter. The order of the equation is simply the highest number of differentiations appeaaring.

7. Jul 23, 2016

### awholenumber

BvU ,

thanks for the replies ...

i am trying to find at least one example for each of these ...

separable equations with only first derivatives
homogeneous equations with only first derivatives
linear equations with only first derivatives
exact equations with only first derivatives

let me see what i can do ...

8. Jul 23, 2016

### awholenumber

i read a little bit more ... and made few more notes ...

An equation containing the derivatives of one or more dependent variables, with respect to one or more independent variables, is said to be a differential equation

they are mainly classified into two ..
ordinary differential equation
partial differential equation ..

then comes first order differential equations to nth order differential equations ...

order is the highest number of the differentiations appearing
degree is the power of the highest order derivative in the equation ...

then there are types of differential equations , depending on their order

separable equations
homogeneous equations
linear equations
exact equations

what is after this ??

partial differential equations ??

9. Jul 24, 2016

### BvU

Work through a lot of exercises

"Classification is the enemy of understanding" is the signature of an esteemed colleague here on PF....

10. Jul 24, 2016

### awholenumber

BvU ,

i had to play around a lot of pictures to understand the different types of differential equations depending on their order ...
exactly , the classification was very confusing ...

somehow , i managed to make up definitions like this ...

then there are types of differential equations , depending on their order

separable equations
homogeneous equations
linear equations
exact equations

from there , i have been reading on partial differential equation ... seem to be an extremely difficult thing to understand properly ...

A partial differential equation is an equation involving functions and their partial derivatives ...

In mathematics, a partial derivative of a function of several variables is its derivative with respect to one of those variables, with the others held constant

i was wondering if i could understand this in terms of a Vibrating string and a Vibrating membrane mentioned in wikipedia ..

Vibrating string

If the string is stretched between two points where x=0 and x=L and u denotes the amplitude of the displacement of the string, then u satisfies the one-dimensional wave equation in the region where 0 < x < L and t is unlimited. Since the string is tied down at the ends, u must also satisfy the boundary conditions

<Mod note: text and image deleted>

i don't really understand all that "Vibrating string" equation ...

but i don't know what else to look for to learn a partial differential equation??

a note to moderators : can i please keep this picture ??
Mod note: No.
if the picture is inappropriate , feel free to delete it ...
Mod note: The image contained multiple copies of exactly the same thing.
Before asking questions about partial differential equations, you need to get some understanding of how to solve ordinary differential equations, preferably by working through the problems in a textbook on ordinary differential equations.

Last edited by a moderator: Jul 29, 2016
11. Aug 11, 2016

### rahul_26

An equation that contains independent variable(usually 'x') some function of 'x',dependent variable(usually'y') some function of 'y' and at least one derivative term of 'y' with respect to 'x' is called a differential equation.
The order of differential equations is the order of the highest order derative that occurs in the equations.
In first order differential equation,the order of the derative is one .
for example-$$x^3\frac{dy}{dx}+logx=5$$ is first order differential equation.

12. Aug 11, 2016

### awholenumber

rahul_26,

thanks a lot for the replies ...