Determine the radius of convergence of the following power series. then test the endpoints to determine the interval of convergence.

σ(21x)^k

the radius of convergence is r =

a. the interval of convergence is {x: x= }
b. the interval of convergence is:

Radius of the convergence is R =

and,

The Interval of convergence is

Step-by-step explanation:

Given function : Σ(21x)^k

Now,

Using the ratio test, we have

R =

or

R =

or

R =

now,

for convergence R|x| < 1

Therefore,

< 1

or

and,

Radius of the convergence is R =

and,

The Interval of convergence is

the answer is somewhere there guys it really . there im just not gonna answer

step-by-step explanation:

but i'm guessing ur first option tho

c: lkllmn.

hope it's you