Hello can someone help me check question 21. I got R=0 I just want to make sure it is correct answer. Please double check my answer.

And please help me Question 11 find the area of the region enclosed by one loop of the curve r = 7cos(2theta) .

Question 21 (5 points) Find the radius of convergence of the following power series. iM: n xn 3n OR = 3 OR = 1 OR = 0 OR = 00 O R = W/ HQuestion 11 (5 points) Find the area of the region enclosed by one loop of the curve: r = 7 cos(20)