How can I solve this second order differential equation?

  • Thread starter Thread starter raul_l
  • Start date Start date
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
2 replies · 4K views
raul_l
Messages
105
Reaction score
0

Homework Statement



dx/dt=1-1/y
dy/dt=1/(x-t)

The Attempt at a Solution



If I take the derivative of the second equation and substitute it to the first one I

[tex]\frac{d^2 y}{dt^2} - \frac{1}{y} (\frac{dy}{dt})^2 = 0[/tex]

but I don't know how to solve this. Could anyone name any methods that could try?
Thanks.
 
Physics news on Phys.org
The trick is to notice
[tex] y''-\frac{1}{y}(y')^{2}=0\Rightarrow\frac{y''}{y'}=\frac{y'}{y}[/tex]
 
[tex] y''-\frac{1}{y}(y')^{2}=0\Rightarrow yy''= y'^{2}[/tex]

Now put in the equation [itex]y=Ae^{Bt}[/itex] and find A and B.