Question 808810
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In the first one, it is not possible to conclude Not D And F because you are given that Not F is true, hence F is false, hence F And anything else is False.


For the second one, assume  Not F, then from C => F, you get Not C by modus tollens.  Not C together with X or C gives you X.  X => Not D, and then Not D => B.  B true makes B or F or D true.  Assume Not D, then Not D => B, and B or F or D is true.  Finally, assume Not B.  Not B together with Not D => B gives you D by modus tollens, and D means B or F or D is true


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
<font face="Math1" size="+2">Egw to Beta kai to Sigma</font>
My calculator said it, I believe it, that settles it
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