X (x+9) (x-1) = 72. find x

X (x+9) (x-1) = 72

lets expand the equation:

(x^2 + 9x) (x - 1) = 72

x^3 - x^2 + 9x^2 - 9x - 72 = 0

x^3 + 8x^2 - 9x - 72 = 0

and factorize again:

x^2 (x + 8) - 9 (x + 8) = 0

(x + 8) (x^2 - 9) = 0

that is:

(x + 8) (x + 3) (x - 3) = 0

double check that x^2 - 9 = (x + 3) (x - 3), that is a subtraction of squares easily factorizable:

So we have:

(x + 8) (x + 3) (x - 3) = 0

which solutions are:

x = - 8, x = - 3, x = 3