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vrble
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1. Suppose A \ B[itex]\subseteq[/itex]C[itex]\cap[/itex]D and x[itex]\in[/itex]A. Prove that if x [itex]\notin[/itex]D then x[itex]\in[/itex]B
2. None
3. Proof: Suppose A \ B[itex]\subseteq[/itex]C[itex]\cap[/itex]D, x[itex]\in[/itex]A, and x[itex]\notin[/itex]D. It follows that our first assumption is equivalent to A due to our third assumption. Thus, B[itex]\subseteq[/itex]C[itex]\cap[/itex]D is disjoint and either x[itex]\notin[/itex]B[itex]\subseteq[/itex]C or x[itex]\notin[/itex]D. Let us temporarily assume that it is the case that x[itex]\notin[/itex]B[itex]\subseteq[/itex]C, then this may be expressed equivalently as x[itex]\in[/itex]B and x[itex]\notin[/itex]C, a contradiction with the definition of subsets, thus x must be an element of B and C provided x[itex]\notin[/itex]DI'm not entirely sure if all of my reasoning is correct.
2. None
3. Proof: Suppose A \ B[itex]\subseteq[/itex]C[itex]\cap[/itex]D, x[itex]\in[/itex]A, and x[itex]\notin[/itex]D. It follows that our first assumption is equivalent to A due to our third assumption. Thus, B[itex]\subseteq[/itex]C[itex]\cap[/itex]D is disjoint and either x[itex]\notin[/itex]B[itex]\subseteq[/itex]C or x[itex]\notin[/itex]D. Let us temporarily assume that it is the case that x[itex]\notin[/itex]B[itex]\subseteq[/itex]C, then this may be expressed equivalently as x[itex]\in[/itex]B and x[itex]\notin[/itex]C, a contradiction with the definition of subsets, thus x must be an element of B and C provided x[itex]\notin[/itex]DI'm not entirely sure if all of my reasoning is correct.
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