Language containing no words starting and ending on “a”
RE= ba*b (none of the words generated from this expression with end or start with "a")
L={bb,bab,baab,baaab,...}
Languages containing only words starting and ending on same letter
RE= ab*a
L={aa,aba,abba,....}
Language of all words with a appears in pairs only
re= a*+b*
Language of all words not ending on “b”
Re= b*a
Language of all words with count of “a “ as multiple of three
RE= (((a*)))
please tell me if these regular expression are correct or no?