Final answer:
The equation P(A + B) = P(A|B) x P(B) = P(A)xP(B|A) refers to the Product Rule in probability theory.
Step-by-step explanation:
The given equation P(A + B) = P(A|B) x P(B) = P(A)xP(B|A) is known as the Product Rule in probability theory.
According to the Product Rule, if A and B are two events defined on a sample space, then the probability of both events occurring (A AND B) is equal to the probability of event B occurring (P(B)) multiplied by the probability of event A occurring given that B has already occurred (P(A|B)).
Similarly, if A and B are independent events, then the probability of both events occurring (A AND B) is equal to the probability of event A occurring (P(A)) multiplied by the probability of event B occurring (P(B)).