maths

Re-arrange:

x^2-2x-8 >0   Factor

(x-4)(x+2) >0

For this to be true, BOTH o these terms must be > 0   or they must BOTH be less than 0

    x-4>0

    x > 4

and   x+2 >0

         x > -2             so the only answer interval that will work is   x >4  for both >0

x-4 <0     x < 4

x+2<0    x<-2           so the only answer here that will work is x <-2

   combined

                          -2> x > 4