Steply

Truth table of p and q

Step by step, with the reason for every step · Truth tables · Discrete Math

Step by step

The question

Question: make the truth table of p ∧ q.

p ∧ q

1 Rows for p and q

Each letter can be true or false.

Two letters give 2 × 2 = 4 rows: every way they can go.

= two letters: 2 × 2 = 4 rows

We make a table: a column for each letter, then a column for each part, from the inside out.

We write T for true and F for false.

T = true, F = false

p: the first half T, the second half F.

This way no row is missed.

q: T, F, T, F, down the column.

2 Column for p ∧ q

We read this sign as and.

∧ = and

p ∧ q is true only when p and q are both true.

p ∧ q: T only when both are T

So it is T only in row 1.

Careful!

And needs both.

One false makes p ∧ q false.

Careful: not T ∧ F = T ✗

The last column is the answer: when p ∧ q is true.

Top to bottom: T, F, F, F.

= p ∧ q: T, F, F, F

3 Check

Let's check row 2 by hand.

In row 2, p is true and q is false.

row 2: p = T, q = F

Put them in: T ∧ F.

It gives F, as in the table.

Right!

T ∧ F = F

Let's look back.

First: rows for p and q.

Then: column for p ∧ q.

Last: check.

Answer
= p ∧ q: T, F, F, F

Your turn

Try this one yourself, then check:

Make the truth table of p → q
Show the answer
p → q: T, F, T, T

More from Truth tables

The whole lesson: Truth tables →