It is not clear what you mean by x^2 minus "factor x". Please add more information and resubmit.
3x squared minus 25x minus 28
6n(2n - 3)
There are no rational factors.
The factors are -1(2x + 1)(3x + 4)
(8w + 7)(8w - 7)
(a + 3)(a - 3)
(5x - 2y)(5x + 2y)
2x squared - 5x - 3 = (2x +1)(x -3)
Without that other number, all you've got is zero.
(x + 1)(x - 8)
(x squared plus the square root of 2) times (x squared minus the square root of 2).