Q3- Write a regular expression for each of the followings. a) All words on ={a,b}, which has a different first and last letter. Example: abbab, bbaaaba b) All words on ={0,1,2,3,4,5,6,7,8,9}, which the decimal number is divisible by 4 . A decimal number is divisible by 4 if the last two digits are divisible by 4. Example: 889132,888976184 c) Try part b again but this time, do not allow leading 0s. d) All words on ={a,b}, that their number of ' a 's mod3 is 2 . na(w)mod3=2 Example: abbabaaa, abbba