Factor completely: \(x^4-81\)

I got: \((x^2+9)(x^2-9)\)

What did I miss?

helperid1839321 Nov 3, 2017

#1**0 **

(x ^2 + 9) ( x^2 - 9)

So far...so good...but notice that x^2 - 9 is also a difference of two squares....

Can you finish it helperid ???

CPhill Nov 3, 2017

#2**+1 **

How didn't I see that on the test...

(x^{2} + 9)(x + 3)(x - 3), right?

helperid1839321 Nov 3, 2017