Verified Answer :

konrad509

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

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