Suppose u={,-2,-1,0,1,2,} is the universal set and r={,-1,1,}. what is r'?

a.{-2,0,2}
b.{,-2,0,2,}
c.{,-2,2,}
d.{-4,-2,2,4}

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236