Answer
Describing the given strings in words of regular sets
Work Step by Step
a) 1∗0
-- Any number of 1s followed by a 0
b) 1*00*
-- Any number of 1s followed by one or more 0s
c) 111 ∪ 001
-- 111 or 001
d) (1 ∪ 00)∗
-- A string of any number of 1s or 00s or some of each in a row
e) (00∗1)∗
-- λ or a string that ends with a 1 and has one or more 0s before each 1
f ) (0 ∪ 1)(0 ∪ 1) ∗00
-- A string of length at least 3 that ends with 00
