document.write( "Question 178748: Given: ~C or D\r
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Algebra.Com's Answer #133795 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "(1)  ~C \/ D \r\n" );
document.write( "(2)  (~A \/ B) -> F \r\n" );
document.write( "(3)  ~B -> C \r\n" );
document.write( "(4)  ~F \r\n" );
document.write( "Prove: D\r\n" );
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document.write( "   I.  ~F                          Given \r\n" );
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document.write( "  II.  ~(~A/\~B)                   By ~F -> ~(~A\/B), the contrapositive of (2)\r\n" );
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document.write( " III.  ~(~A)/\~B                   ~(~A\/B) <-> ~(~A)/\~B DeMorgan's law\r\n" );
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document.write( "  IV.  A/\~B                       ~(~A)<-> A  Negation of negation \r\n" );
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document.write( "   V.  ~B                          Conjunction IV                   \r\n" );
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document.write( "  VI.  C                           V, and (3),  ~B -> C is given\r\n" );
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document.write( " VII.  ~C \/ D                     given\r\n" );
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document.write( "VIII.  C /\ (~C \/ D)              Conjunction of VI with VII\r\n" );
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document.write( "  IX.  (C /\ ~C) \/ (C /\ D)       Distributive law with VIII\r\n" );
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document.write( "   X.  false \/ (C /\ D)           Conjunction of C with its negation is false \r\n" );
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document.write( "  XI.  C /\ D                     \"false\" is the identity for disjunction       \r\n" );
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document.write( " XII.  D                           Conjunction XI\r\n" );
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document.write( "Edwin

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