Explanation:
By plugging specific values of x into the equation looking at the leading integer coefficient and the constant term 8,(-2) and (4) will make f(x)=0 hence both are factors.
We multiply the two factors to obtain a quadratic equation and divide f(x) by it
(x+2)(x-4)=x²-2x-8
Using long division,f(x)/x²-2x-8=2x-1
The factors are therefore (x+2)(x-4)(2x-1)
Finding the zeros gives x=-2,4,½