I want to solve this problem:
$$(x . y . z + x . y + x)$$
Which turns into this when you group $x$
$$x . ( yz + y + 1 ) $$
What I don't understand is why is there a "1" at the end? Does the last $x $ turn into a 1? If so, why?
My math book is unclear, I'm having a hard time.