A∪BA \cup BA∪B
∣A∣+∣B∣−∣A∩B∣|A| + |B| - |A \cap B|∣A∣+∣B∣−∣A∩B∣
A∩B=∅A \cap B = \emptysetA∩B=∅
P(A)×P(B)P(A) \times P(B)P(A)×P(B)
P(A∣B)P(A|B)P(A∣B)
∑i=1nP(B∩Ai)\sum_{i=1}^n P(B \cap A_i)∑i=1nP(B∩Ai)
(A∪B)C(A \cup B)^{C}(A∪B)C
P(n,k)P(n,k)P(n,k)
(np)\dbinom{n}{p}(pn)