Calculus: how do i factor f(x) = x^4 - 8x^2 + 8?

veedub

how do i factor f(x) = x^4 - 8x^2 + 8

I'm trying to get x-intercepts for a graph.

thanks for your help

sahsjing

x^4 - 8x^2 + 8 = (x^2-4)^2 - 8 = (x^2-4-sqrt(8))(x^2-4+sqrt(8))

x-int = +/-sqrt(4+sqrt(8))

and

x-int = +/-sqrt(4-sqrt(8))