document.write( "Question 509899: URGENT:
\n" ); document.write( "P. R->~Q. P->Q therefore ~R\r
\n" ); document.write( "\n" ); document.write( "I need to write out a proof for the following problem using repetition, motus ponen, motus tollens, double negation, etc. This is not graded, but I'm trying to understand it and any help would be appreciated. \n" ); document.write( "
Algebra.Com's Answer #341652 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "To prove:\r\n" );
document.write( "P. R->~Q. P->Q therefore ~R\r\n" );
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document.write( " P         given premise\r\n" );
document.write( " P->Q      given premise\r\n" );
document.write( "----\r\n" );
document.write( "∴Q         modus ponens\r\n" );
document.write( "∴~~Q       double negation\r\n" );
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document.write( "  R->~Q    given premise\r\n" );
document.write( "~~Q\r\n" );
document.write( "-------\r\n" );
document.write( "∴~R        modus tollens \r\n" );
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document.write( "Edwin
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