According to DeMorgan's Theorem, the Boolean expression (AB)' is equivalent to:

According to De Morgan's theorem, the Boolean expression AB is equivalent to A' + B' because the theorem states that the negation of a conjunction (AND) is equivalent to the disjunction (OR) of the negations of the individual variables. In this case, A' represents the negation of A, and B' represents the negation of B. So, A' + B' is the equivalent expression of AB.