Integrating seperable equation

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In summary, there are two separate equations, one with separable variables and one without. The first equation requires integration by parts, but may not have an elementary antiderivative. The second equation is not separable.
  • #1
astonmartin
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Homework Statement



Separable equations

dy/dx = y * e^(sinx +cosy)

and

dy/dx = sin(x^y)

The Attempt at a Solution



For the first problem, I did dy/dx = y * e^(sinx) * e^(cosy) and separated. However, I can't figure out how to integrate e^(sinx)dx on the right. Did I do somehting wrong?

I have no idea what to do on the second one
Thanks for the help!
 
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  • #2
Help pleeeease
 
  • #3
For the first one, my first impression would have been to let u= sin x, giving [tex]\int \frac{e^u}{\sqrt{1-u^2}} du [/tex] and then tried an integration by parts. Checking with the Integrator online however, it seems there is no elementary antiderivative for that function, so don't be surprised if the Integration by parts doesn't work out. Still try it though, because the Integrator has been wrong before.

The Second one isn't actually separable.
 
  • #4
The second, y'= sin(x^y), is NOT separable.

The first is separable but gives integrals that cannot be integrated as elementary functions.
[tex]\int \frac{dy}{ye^{cos(y)}}= \int e^{sin(x)} dx[/tex]
is the best you can do.

Thanks, Gib Z.
 
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  • #5
Small correction - The exponential term on the LHS should be in the denominator. =]
 

1. What is the purpose of integrating separable equations?

The purpose of integrating separable equations is to solve differential equations that can be written in the form of dy/dx = f(x)g(y) by separating the variables and finding an antiderivative for each side. This allows us to find a general solution to the differential equation and solve for the specific solution using initial conditions.

2. How do you know if an equation is separable?

An equation is considered separable if it can be written in the form dy/dx = f(x)g(y), where f(x) and g(y) are functions of only one variable. This means that the x terms and the y terms can be separated on opposite sides of the equation.

3. Can you provide an example of integrating a separable equation?

One example of integrating a separable equation is solving the differential equation dy/dx = 2x/y. We can separate the variables to get ydy = 2xdx. Then, we can find the antiderivatives of each side to get y2/2 = x2 + c. Solving for y, we get the specific solution y = √(2x2 + c).

4. Are there any limitations to integrating separable equations?

Yes, there are limitations to integrating separable equations. Some equations may not be able to be solved using this method, and other equations may require advanced integration techniques. Additionally, initial conditions may not always be available to find a specific solution.

5. How can integrating a separable equation be useful in scientific research?

Integrating separable equations is a powerful tool in solving differential equations, which are commonly used to model physical systems in scientific research. By solving these equations, scientists can gain a better understanding of how different variables affect a system and make predictions about its behavior. This can be useful in fields such as physics, chemistry, biology, and engineering.

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