x2-3x-28
3x^3
(x2+3x-4) (x-4)
If you mean: x2+3x+2 then it is (x+1)(x+2) when factored
x2 + 3x + 7 = 5 ∴ x2 + 3x + 2 = 0 ∴ (x + 1)(x + 2) = 0 ∴ x ∈ {-2, -1}
x2-3x-28
x2 - 3x + 2 = 0
3x^3
The expression x2 + 3x +8 is a quadratic trinomial.
(x2+3x-4) (x-4)
3 - 3x + x2 - x3 = (1 - x)(x2 + 3)
x3 + x2 - 3x - 3 x(x2 + x - 3) - 3
(x2 + 3x + 5)(x2 - 3x + 4)
x2 - 3X - 10 = (X - 5)(X + 2)So, (X2 - 3X -10) / (X-5) = X + 2
x2 + 3x - 40 = (x + 8)(x - 5)
The discriminant of x2+3x+4 is -7 therfore it has no real roots.
If you factor x2 - 3x - 10, you'll get (x-5) (x+2). If your equation is x2 - 3x -10 = 0, then x = 5, and x = -2.