I'm just wondering if my answer is correct:

All the questions are asking for the infinite intersection of n from 1 to infinity of the following intervals:

a. [-1/n,1/n]

b. [-1/n,infinity)

c. (-1/n,infinity)

My answer:

a. {0}

b. [0,infinity)

c. [0,infinity)

I'm not sure if b and c have the same answer :/