- #1
yangbin990
- 2
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Hi,
I am teaching myself the discrete math using the "Discrete Mathematics
Lecture Notes, Yale University, Spring 1999".
And I don't how to prove the practice question below:
Prove that |A∪B|+|A∩B| = |A|+|B|.
The textbook provide answer like below:
The common elements of A and B are counted twice on both sides; the elements in
either A or B but not both are counted once on both sides.
But I think it may be some mathematical way to prove that.
If someone can give me a hand that will be very appreciated.
I am teaching myself the discrete math using the "Discrete Mathematics
Lecture Notes, Yale University, Spring 1999".
And I don't how to prove the practice question below:
Prove that |A∪B|+|A∩B| = |A|+|B|.
The textbook provide answer like below:
The common elements of A and B are counted twice on both sides; the elements in
either A or B but not both are counted once on both sides.
But I think it may be some mathematical way to prove that.
If someone can give me a hand that will be very appreciated.