Answer:
a) Empty set
b)
Step-by-step explanation:
Roster form is a comma separated list form of set.
a) The set of natural numbers x that satisfy x + 4 = 1.
Thus, x is an empty set.
b) set-builder notation for the set {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}.
We use x to represent this set. Now x belongs to natural number and is less than equal to 12.
Thus, it can be written as: