2.2 Set Operations: Discrete Mathematics and its application

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To prove that f(S ∩ T) ⊆ f(S) ∩ f(T), start by taking an arbitrary element x from the subset S ∩ T. Since x is in both S and T, applying the function f gives f(x) in both f(S) and f(T). Consequently, f(x) must be an element of the intersection f(S) ∩ f(T). This establishes the subset relation, confirming that every element of f(S ∩ T) is indeed in f(S) ∩ f(T). The proof demonstrates the fundamental properties of functions and set operations in discrete mathematics.
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Ex 36, p 147.

Let f be a function from the set A to the Set B. Let S and T be the subset of A. Show that

b) f(S \cap T) \subseteq f(S) \cap f(T).

Thanks.
 
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Any time you prove subset relations, you have to show that any element of the subset is an element of the parent set. Let x be an element of the subset, show it is in the parent set.
 
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