document.write( "Question 1089635: ~M, (~M • ~N) → (Q → P), P → R, ~N, therefore, Q → R \n" ); document.write( "
Algebra.Com's Answer #704068 by math_helper(2461)\"\" \"About 
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document.write( "1.  ~M                            Premise\r\n" );
document.write( "2. (~M• ~N)→ (Q → P)              Premise  \r\n" );
document.write( "3.  P → R                         Premise\r\n" );
document.write( "4.  ~N                            Premise\r\n" );
document.write( "    {  To show conclusion:  Q → R  }\r\n" );
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document.write( "5.  ~M• ~N                        1,4  Conjunction (Conj)                   \r\n" );
document.write( "6.  Q → P                         5,2  Modus Ponens (MP)\r\n" );
document.write( "::7.   Q                                  Assumption (begin conditional proof, CP)\r\n" );
document.write( "::8.   P                                  7,6 MP\r\n" );
document.write( "::9.   R                                  8,3 MP\r\n" );
document.write( "10.   Q → R                       7,8,9 End of CP,  and the conclusion\r\n" );
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\n" ); document.write( "Steps 7-9 are conditional. Essentially they show that if Q is true then the logical path through the premises is that R follows, hence Q—>R.
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\n" ); document.write( "Warning: I am a bit rusty with these proofs, so a 2nd opinion won't hurt.\r
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