2. (12 points) {-{a,b,c}, L = {w: w ends with a symbol that does not appear anywhere else in the string}; = {a,b}, L = {w: w contains exactly one occurrence of the substring aaa}; and 3= {a,b,c}, L3= w: w = Xcy, X = {a,b}* and Ix| even, y = {a,b}" and ly] odd}. As examples, bca L, and aca L; baaab L, ab L, and aaaa L; ca L3, aacb L3, bac & L3, aab L3. 2.a (4 points) Write a regular expression that describes L. 2.b (4 points) Write a regular expression that describes L. 2.c (4 points) Write a regular expression that describes L3.