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Non Exact Differential Equation Integrating Factor Calculator

Reviewed by Calculator Editorial Team

This calculator helps you find the integrating factor for non-exact differential equations. The integrating factor is a function that transforms a non-exact differential equation into an exact one, allowing you to solve it using standard methods.

What is an Integrating Factor?

In differential equations, an integrating factor is a function that, when multiplied by the original equation, makes it exact. An exact differential equation is one that can be written in the form:

M(x,y)dx + N(x,y)dy = 0

where M and N are functions of x and y, and the partial derivatives satisfy:

∂M/∂y = ∂N/∂x

If this condition is not met, the equation is non-exact. The integrating factor helps convert it into an exact equation.

How to Use This Calculator

To use the calculator, you'll need to provide:

  • The differential equation in the form M(x,y)dx + N(x,y)dy = 0
  • The partial derivatives ∂M/∂y and ∂N/∂x
  • The integrating factor function type (linear, exponential, etc.)

The calculator will then compute the integrating factor and display the transformed exact equation.

The Formula

The general approach to finding an integrating factor involves solving:

(∂N/∂x - ∂M/∂y) / (M) = ∂(lnμ)/∂x

or

(∂M/∂y - ∂N/∂x) / (N) = ∂(lnμ)/∂y

where μ is the integrating factor. The solution depends on the specific form of the differential equation.

Worked Example

Consider the differential equation:

(2xy + y²)dx + (x + 2xy)dy = 0

Here, M = 2xy + y² and N = x + 2xy. The partial derivatives are:

∂M/∂y = 2x + 2y
∂N/∂x = 1 + 2y

The difference is:

∂N/∂x - ∂M/∂y = (1 + 2y) - (2x + 2y) = 1 - 2x

Assuming the integrating factor is a function of x only, we solve:

dμ/dx = (1 - 2x)/x

Integrating gives:

μ(x) = ∫(1/x - 2)dx = ln|x| - 2x

Multiplying the original equation by this integrating factor transforms it into an exact equation.

FAQ

What if the integrating factor is not found?
If the integrating factor cannot be found, the equation may not be solvable using this method. You may need to consider alternative approaches or check for errors in the equation.
Can this calculator handle all types of non-exact equations?
This calculator is designed for common cases where the integrating factor can be expressed in a standard form. Complex equations may require manual calculation.
What if the equation is already exact?
If the equation is already exact (∂M/∂y = ∂N/∂x), no integrating factor is needed. You can solve it directly using integration.