How to Master Infinite Series and Power Series, Convergence Study and Sum Computation

[@bjornfeuerbacher5514]

You can do the calculation starting at 3:30 also a bit differently: the sum n² x^n can be expressed as x d/dx (x d/dx sum x^n).

[@calculusproblemsandsolutio7914]

You are right. Your approach will give the same result. Thanks for your suggestion.