Okay, I am practicing factoring for an upcoming assignment and I know that this is basic algebra, but I forgot how to attack this polynomial. Every method that I have used so far from simply guessing to using the quadratic formula to long division has failed me in replicating the answer. So either I am attacking this problem wrong up or there is another method that I just forgot.
So here it is: $x^4-2x^2+1=0\\$
The 4 roots of the polynomial are $\pm 1,\pm 1$ (it only has 2 distinct roots).
My confusion is in how to get those values.
Any help in deriving the solution would be greatly appreciated.