Question 189452
Just by looking at the graph of a function,
you can see that the x-intercepts occur
where {{{y=0}}}, so to find x-intercepts,
I just set {{{y=0}}}
{{{y = (x - 4)(x + 2)}}}
{{{0 = (x - 4)(x + 2)}}}
Now I have 2 factors on the right side. If either one 
equal {{{0}}}, then the equation is true.
{{{x - 4 = 0}}}
{{{x = 4}}}
This has to be an x-intercept
{{{x + 2 = 0}}}
{{{x = -2}}}
This has to be the other x-intercept
I'll graph the equation, too
{{{(x - 4)(x + 2) = x^2 - 2x - 8}}}
{{{ graph( 500, 500, -10, 10, -10, 10,x^2 - 2x - 8) }}}