Problem 4: (10 pts) (express the language in terms of basic set operations) a) Prove that if L1 and L2 are regular then L1\L2 (set difference) is also regular b) The symmetric difference of two sets S and S is defined as s,os-rxeS, or xeS but x is not in both S, and S23. Show that the family of regular languages is closed under symmetri difference