Question about the General form to normal form of Diff Eq

In summary, the conversation discusses the general form of a differential equation and attempts to determine if it can be put in the normal form dy/dx=f(x,y). It is concluded that y' cannot be isolated algebraically and further explanation is needed to understand why. There is a question about the possibility of having two roots and if that affects the normal form.
  • #1
Saladsamurai
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7

Homework Statement


The diff eq [itex]x(y')^2-4y'-12x^3=0[/tex] takes the general form. Determine if the equation can be put in the normal form dy/dx=f(x,y)

Well I have tried algebraically to isolate y' and find that I cannot. So my question is, I have decided the answer is no. Now how do I explain why y' cannot be isolated? Maybe this question is stupid...
 
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  • #2
Isolating y' is just solving a quadratic equation. But they have two roots. Does that mean it's not a normal form? That's for you to answer. I don't know.
 

What is the general form of a differential equation?

The general form of a differential equation is an equation that relates an unknown function to its derivatives. It is typically written in the form of F(x,y,y',y'',...)=0, where x is the independent variable, y is the dependent variable, and y', y'', ... represent the derivatives of y with respect to x.

What is the normal form of a differential equation?

The normal form of a differential equation is a specific form that a differential equation can be transformed into. It is usually written as y'=f(x,y), where f(x,y) is a function of both x and y. This form is often used to analyze and solve differential equations.

How do you convert a differential equation from general form to normal form?

To convert a differential equation from general form to normal form, the following steps can be followed:

  • Identify the independent and dependent variables x and y in the equation.
  • Find the highest derivative of y in the equation, denoted by y(n).
  • Rearrange the equation so that y(n) is on the left side and all other terms are on the right side.
  • Divide both sides by y(n) to get the equation in the form y(n)=f(x,y,y',...,y(n-1)).
  • Replace y(n) with y' to get the normal form y'=f(x,y,y',...,y(n-1)).

Why is it important to convert a differential equation to normal form?

Converting a differential equation to normal form can make it easier to analyze and solve the equation. This form is often used in various analytical and numerical methods for solving differential equations. It also helps in understanding the behavior of the solution and making predictions about it.

What are some common techniques used to solve differential equations in normal form?

Some common techniques used to solve differential equations in normal form include separation of variables, integrating factors, substitution, and variation of parameters. Other methods such as Laplace transforms, power series, and numerical methods can also be used depending on the specific equation and its properties.

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