Thefollowingisaproofthatforallsets A and B,ifA B, then A B
Chapter 6, Problem 6.57(choose chapter or problem)
Thefollowingisaproofthatforallsets A and B,ifA B, then A B B. Fill in the blanks. Proof: Suppose A and B are any sets and A B. [We must show that (a) .] Let x (b) . [We must show that (c) .] By denition of union, x (d) (e) x (f) . In casex (g) ,thensinceA B,x (h) .Incasex B, then clearly x B. So in either case, x (i) [as was to be shown].
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