# Potential series method

by matematikuvol
Tags: method, potential, series
 P: 192 Why sometimes we search solution of power series in the way: $$y(x)=\sum^{\infty}_{n=0}a_nx^n$$ and sometimes $$y(x)=\sum^{\infty}_{n=0}a_nx^{n+1}$$???
HW Helper
Thanks
P: 26,160
hi matematikuvol!
 Quote by matematikuvol Why sometimes we search solution of power series in the way: $$y(x)=\sum^{\infty}_{n=0}a_nx^n$$ and sometimes $$y(x)=\sum^{\infty}_{n=0}a_nx^{n+1}$$???
no particular reason …

sometimes one gives neater equations than the other …

they'll both work (provided, of course, that y(0) = 0)
 P: 192 I think that in the case when $$\alpha(x)y''(x)+\beta(x)y'(x)+\gamma(x)y(x)=0$$ if ##\alpha(0)=0## you must work with ##\sum^{\infty}_{n=0}a_nx^{n+k}##, but I'm not sure.
 Quote by matematikuvol I think that in the case when $$\alpha(x)y''(x)+\beta(x)y'(x)+\gamma(x)y(x)=0$$ if ##\alpha(0)=0## you must work with ##\sum^{\infty}_{n=0}a_nx^{n+k}##, but I'm not sure.