Q1. Derive regular expression for the languages given below.

a. Strings with exactly two xs in total or at most three ys followed by an x defined over = {x, y}

b. Strings that contain at least one 2 or one 0 or may be no string at all defined over = {0, 1, 2}

c. Set of strings with only as followed by even number of bs defined over = {a, b}

d. All strings that end with either double a or triple b defined over = {a, b}