Solve X3 plus X2-8X-6 equals 0?

Answer 1

x3 + x2 - 8x - 6 = 0

x3 + 3x2 - 2x2 - 6x - 2x - 6 = 0

x2(x + 3) - 2x(x + 3) - 2(x + 3) = 0

(x + 3)(x2 - 2x - 2) = 0

The second bracket cannot be factorised, so applying the quadratic formula to it gives the answers as

So x = -3 or x = 1 +/-sqrt(3)

that is,

x = -3, x = -0.732051 or x = 2.732051