Question 7 Which one of the following regular expressions defines the language of all strings in which the letter b is never doubled over the alphabet {a b}? This means that no word contains the substring bb. + 1. ba*(a*ab)*a* 2. (1 + b)aa*(1 + b)a* 3. a*(1 + b)a*(ab)*a* 4. a*[(A + b)aa*]*(A + b) Question 8 Which one of the following regular expressions defines the language of all strings that have an even number of a's and an odd number of b's over the alphabet {a b}? Let E = [aa + bb + (ab + ba)(aa + bb)*(ab + ba)]* 1. bE 2. bE + a(E(ab + ba)E) 3. a(E(ab + ba)E) 4. (ab + ba)E