So you created truth tables?

Can you show me how you did this? And how you determined the answers?

there are several ways to determine if a proposition is a tautology or a contradiction.

the easiest one is to make a table,make columns for all the boolean variables and then plug them into the equation and if the equation is always true then it is a tautology,and if it is always incorrect than it is a contradiction.

the other one works only when you have to prove that it is a tautology.it is called *reductio ad absurdum*.

first one is a contradiction

second one is a contradiction

third one is a tautology

fourth one is contingent

and the fifth one is also contingent.

]]>