# Math Help - Constructing truth tables?

1. ## Constructing truth tables?

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)

2. All of those have two variables in them, which means you need $2^{2}$ rows in the table. In general, if you have $n$ variables, you need $2^{n}$ rows. I'll start you off on the first one. I tend to build up truth tables from smaller chunks of the expression:

$
\begin{array}{c|c|c|c}
P &Q &\neg P &(\neg P)\land Q\\ \hline
T &T &F &F\\
T &F &F &F\\
F &T &T &T\\
F &F &T &F
\end{array}
$

Do you see how to continue?

3. Thanks so much, but what I don't understand is when it says "not" "and" "or" what does it mean?

4. Originally Posted by Cockchestner007
Thanks so much, but what I don't understand is when it says "not" "and" "or" what does it mean?
Go to this web site and play around with various examples.
Change to just 'p and q'. Then to 'p or q' etc.