Question 22086
{{{ (16 - x^2) /( x^3 - 2x^2 - 8x) }}}


Factor the numerator and denominator.  The numerator is the difference of two squares, and the denominator has a common factor, which is also a trinomial:
{{{ ((4-x)*(4+x)) /(x* (x^2-2x-8)) }}}
The denominator factors again:
{{{ ((4-x)*(4+x)) /(x* (x-4)*(x+2)) }}} 


Notice that the (4-x) and the (x-4) are negatives of one another, so they divide out, leaving a factor of -1 in the numerator:

{{{ (-1*(4+x)) /(x* (x+2)) }}}
or {{{ -(x+4) /(x* (x+2)) }}}


R^2 at SCC