No Analytic Solution for ODE x^3y'-2y+2x=0

In summary, the given ODE, x^3y' - 2y + 2x = 0, does not have an analytic solution in any neighborhood of x=0. This can be proven using the definition of an analytic solution and the Picard-Lindelof theorem. The solution obtained through the method of separation of variables is not continuous at x=0, which violates the definition of an analytic solution.
  • #1
Malmstrom
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Homework Statement


Consider the following ODE
[tex] x^3y' - 2y + 2x = 0 [/tex]

Homework Equations


Prove that the ODE has no analytic solution in any neighborhood of [tex] x=0 [/tex].

The Attempt at a Solution


Its general solution is [tex]Ce^{-\frac{1}{x^2}}+ e^{-\\frac{1}{x^2}} \int_{x_0}^x - \frac{2e^{\frac{1}{t^2}}}{t^2} dt [/tex] which is not continuous in [tex]x=0[/tex], but I don't think this is unique so I don't know if it helps. Should I try to substitute an arbitrary power series in the equation?
 
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  • #2


you should approach this problem using mathematical rigor and logical reasoning. First, let's define what an analytic solution is. An analytic solution is a solution that can be expressed as a power series, where each term in the series has a finite number of derivatives at a given point.

Now, let's consider the given ODE: x^3y' - 2y + 2x = 0. If we try to solve this using the method of separation of variables, we get the following solution: y(x) = Ce^(1/x^2) + e^(1/x^2) ∫(x_0)^x - (2e^(1/t^2))/(t^2) dt. However, if we try to evaluate this solution at x=0, we get an undefined value. This means that the solution is not continuous at x=0, which contradicts the definition of an analytic solution.

To further prove that there is no analytic solution in any neighborhood of x=0, we can also use the Picard-Lindelof theorem. This theorem states that if a function and its partial derivative are continuous in a given region, then there exists a unique solution to the ODE in that region. However, in this case, the partial derivative of the solution is not continuous at x=0, which means that there is no unique solution in any neighborhood of x=0.

Therefore, we can conclude that the given ODE has no analytic solution in any neighborhood of x=0.
 

Related to No Analytic Solution for ODE x^3y'-2y+2x=0

1. What is an analytic solution for an ODE?

An analytic solution for an ODE (ordinary differential equation) is a function that can be expressed using a finite number of elementary functions such as polynomials, trigonometric functions, and exponential functions. It is a closed-form solution that provides an exact solution to the differential equation.

2. Why is there no analytic solution for the ODE x^3y'-2y+2x=0?

The ODE x^3y'-2y+2x=0 is a non-linear differential equation, meaning that the dependent variable (y) and its derivatives are raised to powers other than 1. In general, non-linear differential equations do not have analytic solutions, and this specific equation cannot be solved using a finite number of elementary functions.

3. Can this ODE be solved using numerical methods?

Yes, this ODE can be solved using numerical methods such as Euler's method, Runge-Kutta method, or the shooting method. These methods involve using a computer to approximate the solution by dividing the interval into smaller subintervals and calculating the values of the function at each subinterval. While not providing an exact solution, these methods can provide a close approximation to the solution.

4. Are there any special cases where an analytic solution for this ODE exists?

No, there are no special cases where an analytic solution for this ODE exists. This is because the equation is fundamentally non-linear and does not have a specific form that can be solved using elementary functions.

5. How important is it to find an analytic solution for a differential equation?

It depends on the context and purpose of solving the differential equation. In some cases, an analytic solution may be necessary for a complete understanding of the system. However, in many cases, a numerical solution is sufficient and can provide a close approximation without the need for an exact analytic solution.

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