I'm hoping this is the right category, since it's set theory. If it's not I'll move it if someone knows a better place for these questions
Prove that A X (B1U B2) = (A X B1) U (A X B2)
I am actually stuck on the B1 B2 in this problem. It's some notation aspect that is keeping me from understanding what the problem is asking for. Are B1 and B2 separate sets?