DE Solution: y' -2y/(x+a) = -1 with Integrating Factor (x+a)^-2

  • Thread starter MACH2
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And the exponent should be -1, not -2. So the left side is y' * (x+a)^-1, not [y' * (x+a)^-2]'.In summary, when solving the differential equation y' -2y/(x+a)=-1, the integrating factor (x+a)^-2 can be used to obtain a 1-parameter family of solutions, with the general solution being y=C(x+a)^2+(x+a). This method can be applied to any equation of the form y'+p(x)y=q(x), as long as p and q are continuous on the interval of the solution.
  • #1
MACH2
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Homework Statement


Solve DE: y' -2 y / (x + a) = -1 where a = constant

Homework Equations


y' + p(x) y = q(x) solving this DE with integrating factor.

The Attempt at a Solution


Use integrating factor (x+a) ^ -2 for above DE,

[ y'(x+a) ^ -2 ]' = - (x+a)^ -2 solving this DE we get

y = C(x+a)^2 + (x+a) this seems to be a solution, C = arbitrary constant

Is this the only solution??
 
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  • #2
MACH2 said:

Homework Statement


Solve DE: y' -2 y / (x + a) = -1 where a = constant

Homework Equations


y' + p(x) y = q(x) solving this DE with integrating factor.

The Attempt at a Solution


Use integrating factor (x+a) ^ -2 for above DE,

[ y'(x+a) ^ -2 ]' = - (x+a)^ -2 solving this DE we get

y = C(x+a)^2 + (x+a) this seems to be a solution, C = arbitrary constant

Is this the only solution??
Yes, your 1-parameter family of solutions contains every particular solution. In fact, every equation of this form, when solved by multiplying by the integrating factor of the exponential of the integral of p, will yield a 1-parameter family of solutions that contains every particular solution, as long as p and q are continuous on the interval of the solution.
 
  • #3
MACH2 said:

Homework Statement


Solve DE: y' -2 y / (x + a) = -1 where a = constant

Homework Equations


y' + p(x) y = q(x) solving this DE with integrating factor.

The Attempt at a Solution


Use integrating factor (x+a) ^ -2 for above DE,

[ y'(x+a) ^ -2 ]' = - (x+a)^ -2 solving this DE we get
The above isn't right. The left side is [y * (x + a)-2]', or in another form d/dx[y * (x + a)-2].
MACH2 said:
y = C(x+a)^2 + (x+a) this seems to be a solution, C = arbitrary constant

Is this the only solution??
 
  • #4
Mark44 said:
The above isn't right. The left side is [y * (x + a)-2]', or in another form d/dx[y * (x + a)-2].

(x+a)^-2 = (x+a) elevated to the -2 power (I am not used to this sites equation editor)

Thanks for your reply,
 
  • #5
slider142 said:
Yes, your 1-parameter family of solutions contains every particular solution. In fact, every equation of this form, when solved by multiplying by the integrating factor of the exponential of the integral of p, will yield a 1-parameter family of solutions that contains every particular solution, as long as p and q are continuous on the interval of the solution.

Thank you for the reply.
 
  • #6
Mark44 said:
The above isn't right. The left side is [y * (x + a)-2]', or in another form d/dx[y * (x + a)-2].
MACH2 said:
(x+a)^-2 = (x+a) elevated to the -2 power (I am not used to this sites equation editor)
It was the left side I was talking about, not the right side. Inside the brackets you should not have y'.
 

Related to DE Solution: y' -2y/(x+a) = -1 with Integrating Factor (x+a)^-2

1. What is a "Re-post Solution to DE"?

A "Re-post Solution to DE" refers to the process of sharing or reposting a solution to a differential equation (DE). This can be done on various platforms, such as online forums or social media, in order to help others who may be struggling with the same problem.

2. Why would someone need a "Re-post Solution to DE"?

There are a few reasons why someone may need a "Re-post Solution to DE." It could be because they are stuck on a particular step or concept in solving the DE, or they may want to compare their solution to others' to check for any mistakes. Additionally, some individuals may simply want to learn different methods or approaches to solving the same DE.

3. How can I find a "Re-post Solution to DE"?

There are several ways to find a "Re-post Solution to DE." One option is to search for the specific DE on online forums or social media platforms, where people often share their solutions and ask for feedback. Another option is to look for resources, such as textbooks or websites, that provide step-by-step solutions to common DEs.

4. Can I trust a "Re-post Solution to DE"?

It depends on the source of the solution. If the solution comes from a reputable source, such as a textbook or a trusted expert, then it is likely trustworthy. However, if the solution is shared by an individual on a forum or social media platform, it is always a good idea to double-check the steps and make sure they are correct.

5. Is it ethical to use a "Re-post Solution to DE"?

Using a "Re-post Solution to DE" can be ethical as long as it is used for learning purposes only. It is important to understand the steps and concepts behind the solution rather than just copying it. Additionally, if the solution is from a source that requires proper citation, it is important to give credit to the original author.

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