Find the product of each sum and difference.
(21+9)(21-9)

Which is the completely factored from of xy^3-x^3y

Which of the following represents a number squared is equal to twenty more than nine times that number ? a) x squared = 9x + 20 b) x squared = 20x + 9 c) x squared > 9 + 20x d) x squared = 9 + x + 20

In the diagram of circle a what is m