Write the function x3 - x2 - 20x + 20 in factored form knowing that one of the roots is 1.
O (x + 1)(x-1) (x+20)
O(x+4) (x - 5) (x - 1)
O(x-1) (x+2√5) (x - 2√5)
○ (x + 1)(x+2) (x - 10)