How to Relate r(t)=x^2(t)+y^2(t) to r'=r-r^3 in Differential Equations?

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SUMMARY

The discussion centers on the relationship between the equations r(t) = x²(t) + y²(t) and r' = r - r³ in the context of differential equations. The user seeks clarification on how to derive the second equation from the first. It is established that r(t) represents the radial distance in polar coordinates, while r' denotes the rate of change of this distance. Understanding this relationship is crucial for solving related differential equations effectively.

PREREQUISITES
  • Understanding of polar coordinates and their representation in differential equations.
  • Familiarity with the concept of derivatives and their notation.
  • Basic knowledge of differential equations, specifically first-order equations.
  • Ability to manipulate algebraic expressions involving functions of time.
NEXT STEPS
  • Study the derivation of polar coordinates in differential equations.
  • Learn about first-order differential equations and their solutions.
  • Explore the concept of stability in nonlinear differential equations.
  • Investigate the applications of r(t) in modeling physical systems.
USEFUL FOR

Students studying differential equations, mathematicians exploring polar coordinate systems, and educators teaching mathematical modeling techniques.

splelvis
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Homework Statement


i had solve the C1 question,
But in c2,
i am not sure what is the relationship between r(t)=x^2(t)+y^2(t) and the r'=r-r^3.
not get the meaning of that question,
how to use the r(t)=x^2(t)+y^2(t) to get the r'=r-r^3?
can anyone explain to me? thanks!
 

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can anyone help?
 

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