- (a*b*)*=(a+b)* this is a property of a regular expression. So option A is correct.
B.(ab)*a=a(ba)* this is also a property of a regular expression. So option B is correct.
C. LHS, (R + RS)*
RHS, take R* as ‘a’ and RS* as ‘b’ then it will become (a+b)* = (a*b*)*
So, (R* + RS*)*=((R*)*(RS*)*)* = (R*(RS*)*)* = (R + RS*)* . [(a*)*=a*]
LHS != RHS. So C false.
D. RHS can generate epsilon(empty string) but LHS can not. So D false.
Correct answers : A,B.
Properties of Regular expressions - GeeksforGeeks
Regular expression - Wikipedia