- For Q1 Q3 use set algebra, laws to prove identities. 1) For all sets A,B,C show that (AB) C = A - (BUC) 2) For all sets A,B,C show that (AUC) - (BA) = AU (CB) 3) For all sets A,B show that (AB) U (BA) = (AUB) - (ANB)