Question 770156
<pre>
{{{(x-4)/(x^2+6x+8)}}}

Denominators can never = 0, so

   x² + 6x + 8 &#8800; 0

(x + 4)(x + 2) &#8800; 0

x + 4 &#8800;  0;  x + 2 &#8800;  0
    x &#8800; -4       x &#8800; -2

So -4 and -2 must be excluded from the domain.

Edwin</pre>