Solving Boolean Algebra: a'b'c' + abc = 1?

[killerfish]

Hi guys,

I'm new to boolean algebra, i couldn't get this through...

a'b'c' + abc = 1 ? or i have to use (abc)' + abc = 1 to get 1 ?

Thanks you.

 

[Shackman]

(abc)' + abc = 1. There are only 2 possible values for abc, and they are 0 and 1. So it is very obvious that if abc isn't 1, then (abc)' is, and vice versa. So 1 or 0 = 1, 0 or 1 = 1. To prove that a'b'c' + abc = 1 isn't always necessarily true, you can construct a truth table with a b c a' b' c' and your answer. You will find that statement is only true when a,b,c are all the same value.