document.write( "Question 978496: D→(B→C), B & −C ├ −D \n" ); document.write( "

Algebra.Com's Answer #599937 by Edwin McCravy(20055) $\"\"$ $\"About$

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document.write( " 1.  D→(B→C)   premise\r\n" );
document.write( " 2.  B&~C      premise\r\n" );
document.write( "       conclusion: ├ ~D\r\n" );
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document.write( " 3.  (D&B)→C,    1, Importation\r\n" );
document.write( " 4.  ~C→~(D&B)   3, Contrapositive\r\n" );
document.write( " 5.  ~C          2, Simplification\r\n" );
document.write( " 6.  ~(D&B)      4,5, Modus Ponens\r\n" );
document.write( " 7.  ~Dv~B       6, DeMorgan's Law\r\n" );
document.write( " 8.  B           2, Simplification\r\n" );
document.write( " 9.  ~~B         8, Double Negation\r\n" );
document.write( "10.  ~D          7,9, Disjunctive Syllogism \r\n" );
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document.write( "Edwin

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