Are the solutions to first order ODE's the same or different for x=a?

  • Context: Graduate 
  • Thread starter Thread starter mhill
  • Start date Start date
  • Tags Tags
    First order Ode
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 3K views
mhill
Messages
180
Reaction score
1
Let be the first order ODE's

[tex]y'(x)g(x)=0[/tex] and [tex]y'(x)g(x)=\delta (x-a)[/tex]

except when x=a the two equations are equal , however the solutions are very different

[tex]y(x)=C[/tex] and [tex]y(x)= C+ \int dx \frac{\delta (x-a)}{g(x)}[/tex]

or using the properties of Dirac delta [tex]y(x)=C+\frac{1}{g(a)}[/tex]

the second equation depends on the form of g(x) whereas the first does not, however except at the point x=a the 2 ODE's are completely equal.
 
Physics news on Phys.org
Why are you saying the two solutions are different? You should be writing C for one and, say, C' for the other- the two constants are not necessarily the same. In fact, all you are saying is that C= C'+ 1/g(a). Which is perfectly reasonable since 1/g(a) is itself a constant.