Let’s find the zeros of the polynomial by factorization.
x2 – 4x + 2x – 8 = 0
x (x – 4) + 2 (x – 4) = 0
(x – 4) (x + 2) = 0
x = 4 , x = -2 are the zeroes of the polynomial.
Thus, α = 4, β = -2
Now let’s find the relationship between the zeroes and the coefficients.
Sum of zeroes = – coefficient of x / coefficient of x2
For x2 – 2x – 8,
a = 1, b = – 2, c = – 8
α + β = – b / a
Here,
α + β = – 2 + 4 = 2
– b / a = – (- 2) / 1 = 2
Hence, sum of the zeros α + β = – b/a is verified.
Now, Product of zeroes = constant term / coefficient of x2
α × β = c / a
Here,
α × β = – 2 × 4 = – 8
c / a = – 8 / 1 = – 8
Hence, product of zeros α × β = c / a is verified.
Thus, x = 4, -2 are the zeroes of the polynomial.