Question

x^2-81

Answer 1

what are you supposed to do with it? factor?

Answer 2

\[a^2-b^2=(a+b)(a-b)\] in this example \(a=x, b=9\)

Answer 3

you have a difference of squares. And like satellite said : a^2 - b^2 = (a + b)(a - b)

so...x^2 - 81 = (x + 9)(x - 9)