Simplify the following xyz + x'(w+z') + yz(w+z') This is what I did: xyz + x'(w + z') + yz(w + z') xyz + x'w + x'z' + yz(w + z') xyz + x'w + x'z' + yzw + yzz' xyz + x'w + x'z' + yzw + 0 I got the answer xyz + x'w + x'z' + yzw However in the book it says the answer is xyz + x'w + x'z'. How could that be? I don't see any way of getting rid of yzw. Please help me with this.