2. (20 pt) Prove or disprove the following statements: (a) (@U *)n(-(*)) = 0. (b) For every language L CE*, (L+)* = L*. 3. (15 pt) For every two languages L1, L2 CS* and the reverse of a language I be defined as IR {wew=for some re L}. Then, prove that (LL)R=LIR