document.write( "Question 1120001: 1. T ⊃ B Prove: L • B (Hint this involves using the Addition Rule)
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Algebra.Com's Answer #735645 by math_helper(2461)\"\" \"About 
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1. T ⊃ B Prove: L • B (Hint this involves using the Addition Rule)
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document.write( "1.  T—>B       Premise
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document.write( "2.  T—>~X      Premise
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document.write( "3.  T          Premise
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document.write( "4.  X          Premise
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document.write( "5.  ~X         3,2  Modus Ponens (MP)
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document.write( "6.  X & (~X)   5,4  Contradiction — we must stop here!
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document.write( "Since the attempted proof contains a contradiction, one can not make a sound proof of  L & B.  Note that  another way to look at this:  it may be possible to \"prove\" L & B  but the proof will not be sound.   This is similar to proving 2=1 when there is a division by zero somewhere in the chain of reasoning.  \r
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