I'm confused on how to solve these calc 2 problems.. I really need your help with detailed steps..! Thank you :)

How can I find the interval of convergence and radius of convergence..?? Can you please guide me with clear and detailed steps..?

a. ??n=0??4n(?1)n+1xn??

b. ??n=0??n!x5n??

c. ??n=0??(n+1)4n2(x?3)n+1??

POWER SERIES FOR ELEMENTARY FUNCTIONS Interval of Function Convergence -= 1 - (x - 1) + (x - 1)2 - (x - 1)3 + (x - 1)4 - . . . + (-1)"(x - 1)" + . . . 0 +x-x+. ..+(-lux+... -1