Respuesta :

konrad509
[tex]x^2-81=(x-9)(x+9)[/tex]
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!

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