please help me...for the power series summation of n^4x^n/2(n-1)factorial....find the radius

Question

and interval of convergence...

so far i am guessing that radius is equal to x and interval of convergence is (-infinty to positive infinity) is that correct?



You need to do a ratio test first. Have you done that?

no i didnt...how would ratio test help me?

K I DID USE THE RATIO TEST and i got the limit equal to 0...so does that mean that the radius of convergence is equal to infinity? so is the radius x?

For what values of x does it converge in the ratio test? Doesn't that determine the radius of convergence?