L1={u €E•[u ends with aa}. 12 = {u €E•[u ends and begins with different letters }. L3 = {u €I•|u contains abba). L4 = {u €E•[u is of the form anbamfor n,m> 0}. Given the above languages: (a) Use the...

Extracted text: L1={u €E•[u ends with aa}. 12 = {u €E•[u ends and begins with different letters }. L3 = {u €I•|u contains abba). L4 = {u €E•[u is of the form anbamfor n,m> 0}. Given the above languages: (a) Use the set operators 'union' and 'complement' to describe L5 = L1 n L2. (b) Prove that L5 is regular.