[SOLVED] i confuse A question of optimize expression in SoP and Pos

[songdiandian]

the (b), i think it's not necessary to distributive expression,because it will became complex.my way is like this:
F'={EXPRESSION}'，On the basis of Demorgan's defining,F'=ABD+A'BC+AB'D+B'CD,optimized,then F'=AD+A'BC+B'CD.use Demorgan's defining again.
F''=F=(A'+D')(A'+B+D')(B+C'+D').This is probably the answer of the question.but F=(C'+D')(A'+D')(A+B'+C') is the correct answer.why?

 

[Rohitchampion]

hey SoP and PoS form has every variable or its complement in each term. so F=(C'+D')(A'+D')(A+B'+C') is not PoS form. you will have to add AA'+BB' in first term, BB'+CC' in second and DD' in last one.

 

[songdiandian]

thank you for helping.