Calculus (Dynamical Systems and iterated sequences)

okay so Consider the dynamical system defined by iterating the function f(x) = 1 − x^2, that is, for a given initial point x0 we consider sequences ⟨xn⟩ obtained by iterating, xn+1 = f(xn), n ∈ N.

Calculate f^(2)(x) = f(f(x)). Find all period-2 points which are not already fixed points of f(x). Call them p1, p2 with p1 < p2.

so I found f(f(x)) = 2x^2 -x^4 then set x = f(f(x)) to get -x^4 +2x^2 -x = 0 but i can't figure out how to factor it and I'm not sure if I'm even doing it right. any help is appreciated!