Hello, gabet16941!
Use the ratio test to find the radius of convergence and interval of convergence.
. .
Hence: .
The series converges for all values of
The interval of convergence is: .
Use the ratio test to find the radius of convergence and interval of convergence of the power series.
i bealive it would be the sum from 0 to infinity of (3x)^n/n! and using the ratio test i get 3x but after that not sure how to get radius and the interval