Solution

Any combination of strings in set {ab, aa, baa} will be in L*. 

Consider each option one by one:

Option 1) baaaaabaaaab

It cannot be partitioned as a combination of strings in set {ab, aa, baa}. 

Option 2) abaabaaabaa

It can be partitioned as a combination of strings in set {ab, aa, baa}. The partitions are “ab aa baa ab aa”.

Option 3) aaaabaaaa

It can be partitioned as a combination of strings in set {ab, aa, baa}. The partitions are “aa ab aa aa”. 

Option 4) baaaaabaa

It can be partitioned as a combination of strings in set {ab, aa, baa}. The partitions are “baa aa ab aa”. 

Hence only baaaaabaaaab is NOT in L*.