Question 654642
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1.  a --> c  


2. ~a --> b


3. ~c        /b


4. ~a        1 & 3: modus tollens


5. ~a --> b  2: given


6.  b        4 & 5: QED



</pre>
John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
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