Comparing given polynomial with the general form ax2+bx+c,
We get, a = 1, b = - 2 and c = -8
We have, x2–2x−8 = x2–4x+2x–8
= x (x-4) +2 (x-4)
= (x+2) (x-4)
Equating this to 0, we will get the values of 2 zeroes of the polynomial.
(x-4)(x+2) = 0
⇒ x = -2 and 4 are two zeroes.