- #1
jessicaw
- 56
- 0
Homework Statement
find the roc of:
[tex]\sum_{n=0}^{\infty}\frac{(n!)^3}{(3n)!}z^{3n}[/tex]
Homework Equations
limsup
ratio test
The Attempt at a Solution
i think use of limsup is quite difficult as factorial there.
but i do not know how to use the ratio test because z is another variable. It means there are two independent variable, but ratio test is for one variable(i.e. n)only, rite?
Also besides ratio test and limsup, are there other methods to find the "roc"?
thx!