Differential equation question

In summary, the conversation is discussing a homework question involving the equation (1/z) * dz/dx = a* \sqrt{dy/dx}, where x,y,z are variables and a is a constant. The solution involves taking the integral of both sides and potentially using a substitution with one of the variables to solve for z. There is also a question about whether or not certain calculations with square roots and differentials are allowed.
  • #1
redtree
285
13
This is not a homework question, but I am posting here so as not to run afoul of the "rules."

Homework Statement



[tex] (1/z) * dz/dx = a* \sqrt{dy/dx}[/tex]

where x,y,z are variables and a is a constant.

Homework Equations



See above

The Attempt at a Solution



[tex]\left[ (1/z) * dz/dx = a*[tex]\sqrt{dy/dx} \right] *dx [/tex]

Thus,
[tex] dz/z = a* \sqrt{dy * dx}[/tex]

[tex]\int dz/z [/tex] = [tex]\int a* \sqrt{dy * dx} [/tex]

[tex] ln(z) = \int a \sqrt{dy * dx}[/tex]

??
 
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  • #2
And are you allowed to do something like:
[tex]
(dz/z)^2 = a^2* dy * dx
[/tex]
 
  • #3
(1) I would say: first get rid of the square root, then continue. Those calculations with square roots and bare differentials are questionable.

(2) Since there are three variables (x,y,z), what are you supposed to do? For example: Let y be ANY function of x, plug it in and get a differential equation to solve for z... Would that be good for you?
 

1. What is a differential equation?

A differential equation is a mathematical equation that relates the rate of change of a function to the function itself. It involves one or more derivatives of an unknown function.

2. What is the purpose of solving differential equations?

The purpose of solving differential equations is to find the relationship between a function and its derivatives. This allows us to predict the behavior of a system over time and make informed decisions in various fields, such as physics, engineering, and economics.

3. What are the different types of differential equations?

The different types of differential equations include ordinary differential equations (ODEs), partial differential equations (PDEs), and stochastic differential equations (SDEs). ODEs involve only one independent variable, while PDEs involve multiple independent variables. SDEs also include a random component.

4. How do you solve a differential equation?

The method for solving a differential equation depends on its type and order. ODEs can be solved using analytical methods, such as separation of variables or integrating factors, or numerical methods, such as Euler's method or Runge-Kutta methods. PDEs often require numerical methods due to their complexity.

5. What are some real-world applications of differential equations?

Differential equations have many applications in fields such as physics, engineering, biology, economics, and finance. They can be used to model and predict the behavior of physical systems, population growth, chemical reactions, heat transfer, and many other phenomena.

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