Differential equations time evolution

Katy96
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Homework Statement


upload_2015-8-6_16-50-11.png


Homework Equations

The Attempt at a Solution


Any help would be appreciated
 
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katy96:
Please try to post your HW problems in the correct HW forum.

Questions about differential equations should be posted in the Calculus HW forum.

Thanks.
 
SteamKing said:
katy96:
Please try to post your HW problems in the correct HW forum.

Questions about differential equations should be posted in the Calculus HW forum.

Thanks.
It was given in a physics class as part of mechanics assignment
 
Katy96 said:
It was given in a physics class as part of mechanics assignment
It's still a calculus problem so should be posted in the relevant section.

For your question, essentially you want to eliminate every derivative of ##y## and have a DE which just involves ##x## and its time derivatives. Start by differentiating ##\frac{dx}{dt}## to obtain an equation for ##\frac{d^2 x}{dt^2}## which will leave you with 3 equations. You can use these to eliminate ##y## and its derivatives.
 
If this was given as a homework problem, surely you have been given some instruction in solving such problems. There are, in fact, several ways to solve this problem. We have no idea which method would be appropriate for you without knowing what methods you have learned. Part of the problem tells you to "Combine these to form a second order equation for x(t) and find the general solution for x(t)". Do you know how to do that?

Start by differentiating both sides of the given equation that starts "dx/dt= " with repect to t. The result will have a second order derivative of x(t) and a derivative of y(t). Use the other equation to replace that "dy/dt".
 
Or else you can obviously eliminate y between these two eqs. but then you are left with dy/dt in the result. Differentiating first eq. you get dy/dx in terms of x and derivatives and t only which you can then substitute into the other equation you just got.

Not something which requires you to be 'taught' a 'method' IMHO, just a bit of initiative or at most to be told it's possible.
 
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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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