Question 1204396
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This is one way to form the truth table. 
There are ways to condense things, but I prefer the more expanded out version to see how each piece is formed.
Feel free to go with the condensed table if you want.
<table border = "1" cellpadding = "5"><tr><td></td><td></td><td></td><td></td><td></td><td>Premise</td><td>Premise</td><td>Premise</td><td>Conclusion</td></tr><tr><td>K</td><td>M</td><td>H</td><td>~H</td><td>M v ~H</td><td>K -> (M v ~H)</td><td>M -> H</td><td>M -> K</td><td>K -> H</td></tr><tr><td>T</td><td>T</td><td>T</td><td>F</td><td>T</td><td>T</td><td>T</td><td>T</td><td>T</td></tr><tr><td>T</td><td>T</td><td>F</td><td>T</td><td>T</td><td>T</td><td>F</td><td>T</td><td>F</td></tr><tr><td>T</td><td>F</td><td>T</td><td>F</td><td>F</td><td>F</td><td>T</td><td>T</td><td>T</td></tr><tr><td>T</td><td>F</td><td>F</td><td>T</td><td>T</td><td><font color=red size=4>T</font></td><td><font color=red size=4>T</font></td><td><font color=red size=4>T</font></td><td><font color=red size=4>F</font></td></tr><tr><td>F</td><td>T</td><td>T</td><td>F</td><td>T</td><td>T</td><td>T</td><td>F</td><td>T</td></tr><tr><td>F</td><td>T</td><td>F</td><td>T</td><td>T</td><td>T</td><td>F</td><td>F</td><td>T</td></tr><tr><td>F</td><td>F</td><td>T</td><td>F</td><td>F</td><td>T</td><td>T</td><td>T</td><td>T</td></tr><tr><td>F</td><td>F</td><td>F</td><td>T</td><td>T</td><td>T</td><td>T</td><td>T</td><td>T</td></tr></table>
T = true
F = false


Here is a review of various truth table rules
<a href = "https://www.algebra.com/algebra/homework/Conjunction/truth-table1.lesson">https://www.algebra.com/algebra/homework/Conjunction/truth-table1.lesson</a>


The row I've marked in red, <font color=red>line 4</font>, represents the situation where we have all true premises, but they lead to a false conclusion.
This happens when: K = true, M = false, H = false


Because we have all true premises leading to a false conclusion, we have an invalid argument.  


Answer:  <font color=red size=4>Invalid; fails in 4th line.</font>


Side note: line 2 comes close but not all premises are true here.


Another example of an invalid argument is found in problem 3 of this link
<a href="https://www.algebra.com/algebra/homework/Proofs/Proofs.faq.question.1204272.html">https://www.algebra.com/algebra/homework/Proofs/Proofs.faq.question.1204272.html</a>
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