1. The problem statement, all variables and given/known data Find the radius of convergence and the interval of convergence 2. Relevant equations A_n = Ʃ sum n =1 to infinity [((-1)^n) x^(2n+1)]/(2n+1)! 3. The attempt at a solution All I thought was to use the ratio test so I did A_(n+1) /A_n = ((x^(2n+1))/(2n+1)!) ( (2n+1)!)/ [x^(2n+1)] I got |x^2| limit n ---> |x^2 / 4n^2 +10n +6 | when I simplified and such. So the limit is equal to 0 so my interval of convergence is 0 ? and R = 0?