Sign up ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Describe the orbits of $$\frac{{\rm d}r}{{\rm d}t}=r(r-2)(r-4),$$ where $(r,t)$ is the usual polar co-ordinates.

Can we do solve this problem without integration? What is meant by 'describe' here? I am trying to use the Cantor-Bendixon Theorem , but I cannot really solve it.

share|cite|improve this question
Hint: Think of it as a one-dimensional dynamical system, where $t$ is time, and draw the phase portrait on the $r$ axis. – Hans Lundmark Sep 5 '12 at 14:27
Maybe this helps: W|A... – draks ... Sep 5 '12 at 15:11

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.