so according to factor theorem, x^4 + x^2 + 1 shouldn't be factorable since no value of x can make the equation equal to 0, and also, when graphed, it has no x-intercepts in the set of real elements.. but it is factorable... as (x^2 + x + 1)(x^2 - x + 1). so my question is what method was used to factor this? also, how can you tell when a polynomial that can't be factored using factor theorem is factorable?