Proof of probability addition formula of three events ABC three events, proof P (aubuc). I know the formula, the process of proof Just look at the picture, I can understand. The key is to show it.

Let d = AUB, P (aubuc) = P (Duc) = P (d) + P (c) - P (DC), ----- (1) P (d) = P (a) + P (b) - P (AB), ----- (2) P (DC) = P (acubc) = P (AC) + P (BC) - P (ABC). ----- (3) (2) and (3) be substituted into (1)

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1. Does the independent event satisfy the probability addition formula
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