Answer:
(p ∧ q)’ ≡ p’ ∨ q’
Explanation:
First, p and q have just four (4) possibilities, p∧q is true (t) when p and q are both t.
p ∧ q
t t t
t f f
f f t
f f f
next step is getting the opposite
(p∧q)'
f
t
t
t
Then we get p' V q', V is true (t) when the first or the second is true.
p' V q'
f f f
f t t
t t f
t t t
Let's compare them, ≡ is true if the first is equal to the second one.
(p∧q)' ≡ (p' V q')
f f
t t
t t
t t
Both are true, so
(p ∧ q)’ ≡ p’ ∨ q’