Using FOIL (First Outside; Inside, Last), we find our product.
(7x - 3)(7x + 3) // Given 7x * (7x + 3) // First Outside 49x^2 + 21x // Distribute (remember this) -3 * (7x + 3) // Inside Last -21x - 9 // Distribute (remember this) 49x^2 + 21x - 21x - 9 // Add both answers (the one from Outside and the one from Inside) 49x^2 - 9 // Simplify. This is your answer
You can do this, or you can remember that this is a factor for a difference of squares, where
