Write the dual of each statement.

(x + y)(x+1) = x + xy + y

As the books skips all of the in between steps, i can only postulate on what I'm supposed to do. (I'm thinking of using a supplemental book because this book isn't helpful)

Since the book also uses a example as a definition, I'm guesing that the dual of an equation is one that is fundamentally the same but in a different form.

What I did:

$\displaystyle (x+y)(x+1) = x + xy + y$

$\displaystyle x^2 + x + xy + y = x(y+1) + y$

However, the answer is $\displaystyle xy + x0 = x(x+y)y$

The professor lost me in the lecture, though I hope to meet with him later to work on some other problems.

Thanks!