(y^2cosx-3x^2y-2x)dx+(2y Sinx-x^3+ln Y)dy=0

3 min read Jun 17, 2024
(y^2cosx-3x^2y-2x)dx+(2y Sinx-x^3+ln Y)dy=0

Solving the Differential Equation: (y^2cosx - 3x^2y - 2x)dx + (2ysin x - x^3 + ln y)dy = 0

The given differential equation is:

(y^2cosx - 3x^2y - 2x)dx + (2ysin x - x^3 + ln y)dy = 0

This equation is a non-exact differential equation. We can check this by verifying if the following condition holds:

∂M/∂y = ∂N/∂x

Where:

  • M = y^2cosx - 3x^2y - 2x
  • N = 2ysin x - x^3 + ln y

Calculating the partial derivatives:

  • ∂M/∂y = 2ycosx - 3x^2
  • ∂N/∂x = 2ycosx - 3x^2

Since ∂M/∂y = ∂N/∂x, the equation is exact. This means we can find a potential function, u(x,y), such that:

  • ∂u/∂x = M
  • ∂u/∂y = N

To find u(x,y), we integrate M with respect to x:

u(x,y) = ∫(y^2cosx - 3x^2y - 2x)dx = y^2sinx - x^3y - x^2 + g(y)

Here, g(y) is an arbitrary function of y, as the partial derivative with respect to x will eliminate any function solely of y.

Now, we differentiate u(x,y) with respect to y and equate it to N:

∂u/∂y = 2ysinx - x^3 + g'(y) = 2ysin x - x^3 + ln y

This implies: g'(y) = ln y

Integrating both sides with respect to y: g(y) = yln y - y + C

Substituting g(y) back into the potential function:

u(x,y) = y^2sinx - x^3y - x^2 + yln y - y + C

The general solution to the differential equation is given by:

u(x,y) = C

Therefore, the solution to the given differential equation is:

y^2sinx - x^3y - x^2 + yln y - y = C

Where C is an arbitrary constant.

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