Origin as the Only Critical Point: Solving Differential Equations

Click For Summary

Homework Help Overview

The discussion revolves around demonstrating that the origin is the only critical point for a system of differential equations defined by the equations x' = -x - x^3 and y' = -y - y^5. The original poster expresses uncertainty due to missed lectures and seeks assistance in understanding the problem.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to clarify the second equation due to a potential typographical error. There is an emphasis on ensuring the accuracy of the equations before proceeding with finding critical points. Some participants suggest differentiating the functions and setting them to zero to identify stationary points.

Discussion Status

The conversation is ongoing, with participants questioning the correctness of the equations and exploring the implications of the identified critical points. There is no explicit consensus, but guidance on the differentiation process has been provided.

Contextual Notes

There is a noted concern regarding a possible typo in the second equation, which may affect the interpretation of the problem. The original poster's missed lectures due to a medical issue adds context to their request for help.

Kamekui
Messages
12
Reaction score
0

Homework Statement



Show the origin is the only critical point

Homework Equations



x'= -x-x3
y-= -y-y5

The Attempt at a Solution


I'm not really sure how to go about this. I missed a few lectures due to a medical issue, and now were at the end of the semester and I can't get in touch with the professor. Any help would be appreciated.
 
Physics news on Phys.org
Kamekui said:

Homework Equations



x'= -x-x3
y-= -y-y5

Your second equation doesn't make sense. The very first step when asking for help, is to always make sure that you have typed your question correctly. There is a minus after y. Is there supposed to be another constant or variable after the minus sign? Or is that minus sign not supposed to be there?

Anyway, to find the critical point, you should differentiate the function with respect to the independent variable and then equate to 0.
 
Kamekui said:

Homework Statement



Show the origin is the only critical point

Homework Equations



x'= -x-x3
y-= -y-y5

The Attempt at a Solution


I'm not really sure how to go about this. I missed a few lectures due to a medical issue, and now were at the end of the semester and I can't get in touch with the professor. Any help would be appreciated.

sharks said:
Your second equation doesn't make sense. The very first step when asking for help, is to always make sure that you have typed your question correctly. There is a minus after y. Is there supposed to be another constant or variable after the minus sign? Or is that minus sign not supposed to be there?

Anyway, to find the critical point, you should differentiate the function with respect to the independent variable and then equate to 0.

It doesn't take much imagination to figure out that the second equation is ##y'=-y-y^5##. This is a system of two differential equations. The stationary points are where ##x'## and ##y'## are simultaneously zero.
 
LCKurtz said:
It doesn't take much imagination to figure out that the second equation is ##y'=-y-y^5##. This is a system of two differential equations. The stationary points are where ##x'## and ##y'## are simultaneously zero.

I kinda guessed, but i preferred to point it out to the OP. Previously, in other threads with typo errors, i had guessed and assumed, but it turned out that i was wrong, and i got flamed by the poster/s. So... I'm not doing the same mistake of assuming anything again.
 

Similar threads

  • · Replies 27 ·
Replies
27
Views
2K
Replies
10
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
3
Views
2K
Replies
9
Views
3K
Replies
2
Views
1K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 10 ·
Replies
10
Views
2K
Replies
7
Views
2K