I'm not sure that I understand your question. Which 'plus sign in front of the c'? In the first few lines of working there is no c with a plus sign in front.
Originally Posted by Paymemoney
And nowhere in my working does this expression appear.
If you're going to make a success of Boolean Algebra, you'll have to learn to be meticulously accurate in writing down exactly what you mean. There's no room for even the smallest error.
Perhaps you mean: how did I simplify the first bracket in the first line of my working by removing its last negative sign? In other words, how did I do:
[c(u + v')']'[...]If that is what you meant, then replace (u + v') by w. So we get:
=[c' + (u + v')][...]
=[c' + ((w)')'][...]
=[c' + w]