You may describe algorithms informally, as long as your description is clear and complete. No need to give programs or Turing machines.

(20%) Let L, K-{0, 1)' be disjoint languages. (a) Give an example where L, K are both undecidable, and their union is decidable. (b) Give an example where L, K are both undecidable, and their union is undecidable. (c) Show that if L is decidable and K is undecidable, then LUK must be undecidable