(x+5)(x-6)(3x-1) taken in pieces, we have
(x + 5) (x - 6) = x(x - 6) + 5( x - 6) = x^2 - 6x + 5x - 30 = x^2 - x - 30
And this result times the last term, (3x - 1) =
x^2(3x - 1) - x(3x- 1) - 30(3x - 1) = 3x^3 - x^2 - 3x^2 + x - 90x + 1 = 3x^3 - 4x^2 - 89x + 30
