how to find its radius of convergence, it tried the ratio test
but it doesnt work
I think you'll find that .
So the ratio test forces the requirement |z| < 1. Then you must test the cases z = 1 and z = -1 for convergence, which should be very simple to do .....
So the ratio test forces the requirement |z| < 1. Then you must test the cases z = 1 and z = -1 for convergence, which should be very simple to do .....
No. is complex so . There are infinitely many points to check.