SOLUTION: I also got this one wrong, can someone show me the correct way to solve this, please? Consider the formula n(A U B) = n(A) + n(B) - n(A ∩ B). (a) Show that this relati

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Question 190258: I also got this one wrong, can someone show me the correct way to solve this, please?
Consider the formula n(A U B) = n(A) + n(B) - n(A ∩ B).

(a) Show that this relation holds for A = {1, 2, 3, 4} and B= {2, 4, 5, 6, 7, 8}
(b) Make up your own two sets A and B, each consisting of at least six elements. Using these two sets, show that the relationship above holds.
(c ) Use a Venn diagram and explain why the relation holds for any two sets A and B.

Answer by user_dude2008(1862)   (Show Source): You can put this solution on YOUR website!
A ∩ B = set with common elements in A & B = {2,4}

n(some set) = # of elements in given set


n(A) = 4
n(B) = 6
n(A ∩ B) = 2


n(A U B) = n(A) + n(B) - n(A ∩ B).

n(A U B) = 4 + 6 - 2

n(A U B) = 8


Ans: n(A U B) = 8

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