Provide a regular expression that shows the set of strings

Question

Answer the subsequent questions and also justify your answers with appropriate examples

Question 1: Using proper English, describe the explain regular language

Part 1: (ab)*aa

Part 2: b*a*

Question 2: Provide a regular expression that represents the explained set:

Part 1) The set of strings over {a, b, c} in which all the a's precede the b's and c's.

Part 2) The set of strings over {a, b, c} that contain odd number of a's

Question 3: Construct DFA without ?-transition that accepts the subsequent language

Part 1) (ab?a)?

Part 2) (ab)*(ba)*

Question 4: Provide a regular expression that shows the set of strings over {a, b} thatcontain at least one b if its length is at least four.