For the other, you need one principle. If two numbers mutiplied gives zero (0), what is it that we know about the numbers? There is something VERY SPECIFIC about at least one of the numbers. It doesn't work for anything except zero (0).
What say you? What is the great principle that will help you solve this problem?
Short Way: Recognize that this is a special factorization pattern known as "Difference of Squares" (Easy to multiply in your head, once you understand the principal of "Difference of Squares"; google it.)
Long Way: Carry out the multiplication by hand (using polynomial multiplication) and simplify. The set of steps is known as "FOIL" (Still easy, but more steps than the difference-of-squares pattern; tk showed you the steps for FOIL, but you could google "FOIL", too, to learn more.)