Proof: A is a Subset of B iff A Union B Equals B | Set Theory, Subsets

A is a subset of B if and only if A union B equals B. We'll be sharpening our set theory proof skills with this simple result in today's video set theory lesson!

Think of the result like this, if A is contained in B, then adding the elements of A to B doesn't change B at all, because B already contains the elements of A, and so their union is still just B. It's a good result to get comfortable with proving set equality and biconditional statements as well!

Check out my lesson on subsets:    • What is a Subset?  



If you are preparing for Set Theory or in the midst of learning Set Theory, you might be interested in the book I learned set theory and proofs from. It is “Book of Proof“ by Richard Hammack. Check out the book and see if it suits your needs! You can purchase the textbook using the affiliate link below which costs you nothing extra and helps support Wrath of Math!

PURCHASE THE BOOK: https://amzn.to/2TwTzG0
Or download the book for free: https://www.people.vcu.edu/~rhammack/...



I hope you find this video helpful, and be sure to ask any questions down in the comments!

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Vallow Bandcamp: https://vallow.bandcamp.com/
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