Question

please help fan and medal whatever you want.
What are the factors of x2 − 81?

Answer 1

$x^2-81=(x-9)(x+9)$

Answer 2

x^2-81
(x+9)(x-9)
x*x=x^2
x*-9= -9x
x*+9= 9x
^^^ These last two cancel each other out
+9*-9 = -81 (neg times pos is neg)
Left with (x^2-81)

I used * as a multiplication sign because an x is confusing when x is your variable
Look up the Box Method- It makes factoring easier!