4. A regular expression for the language over the alphabet fa, b} with each string having an even number of a's is (b*ab*ab*)*b*. Use this result to find regular expressions for the following languages a. a language over the same alphabet but with each string having odd number of a's. (3 points) b. a language over the same alphabet but with each string having 4n (n >- 0) a's. (3 points) 5. If a regular expression for the language over the alphabet (a, b) with no string containing the substring bb is (a+ba)*(A+b), then what is the regular expression for the language over the same alphabet with no string containing the substring a. bbb? (3 points) b. bbbb? (3 points)