Ok, so I got a recent homework back for which I had to find the interval of convergence for the following series:
sigma starting at j=3 and going to infinity of:
3/(2-j) * (x+3)^j
Now, I found the interval of convergence by doing the following:
a_n+1/a_n = (n-2)/(n-1) * |x+3|
If |x+3| < 1, then the series is absolutely convergent.
-1 < x+3 < 1
Subtracting 3 from all sides, I got
-4 < x < -2, the interval of convergence.
My teacher wrote on my paper that I should check the endpoints to see if they are included. How do I go about this (my teacher went over this in class, but I seem to have lost the paper I wrote it on)?