1. The problem statement, all variables and given/known data find the interval of convergence of [tex]\sum[/tex][(2k+1)!/((2k)((k!)2)]* [xk] 2. Relevant equations Ratio Test 3. The attempt at a solution I already found that it converges on (-1/2, 1/2) by using power series with b=0 and testing the rest of it as ak. However, I am unsure about the end points. I tried using the ratio test with x = (-1/2) and I get the limit to be 1 so the test fails. What test would I be able to use? Any help is greatly appreciated.