Date: Dec 17, 2012 9:26 AM
Author: J Cadman
Subject: Re: Disc.Math homework problem

Use De Morgan's law to separate out all the 'ands', then

AD' + A'B' + B'D' = A'+D + A+B + B+D, notice that D+D=D and B+B=B, so the above becomes

A'+D + A+B which can be written as
(A'+D) + (A+B),
now use De Morgan on each bracket to obtain AD' + A'B'