how would you construct a truth table for these compound proposition? im so confused
(a) if P then ((notP) and Q)
(b) P and ((not P) and Q)
(c) (not P) or (not Q)
All of those have two variables in them, which means you need rows in the table. In general, if you have variables, you need rows. I'll start you off on the first one. I tend to build up truth tables from smaller chunks of the expression:
Do you see how to continue?
Go to this web site and play around with various examples.
Change to just 'p and q'. Then to 'p or q' etc.