Regular expression for having atleast 2 a's
(1). (a + b)* a (a + b)* a (a + b)*
(2). (a + b)* a b* a (a + b)*
(3). b* a (a + b)* a (a + b)*
(4). (a + b) * a (a + b) * a b*
(5). b* a (a + b)* a b*
I know 1-4 are correct and just want help with 5th one . Please tell me is it correct or not with reason.
Thanks in advance....