Answer:
x² - 1
Step-by-step explanation:
When x - 1 = 3 and x + 1 = 5 we know that x = 4 so (x - 1)(x + 1) = 4² - 1 when x = 4, 5² - 1 when x = 5 and so on. If you look carefully you will notice a pattern, the product is always x² - 1 so the answer to the blank is x² - 1.
