for a fraction, if the denominator turns to 0, the fraction becomes undefined, and therefore, that's a restriction on a rational.
now, what values of "x" makes the denominator 0? let's check,
x+2 = 0
x = -2
so, if "x" ever becomes -2, then you'd get
[tex]\bf \cfrac{x+9}{x+2}\implies \cfrac{x+9}{-2+2}\implies \implies \cfrac{-2+9}{-2+2}\implies \stackrel{und efined}{\cfrac{7}{0}}[/tex]
so, the domain, or values "x" can take on safely, are any real numbers EXCEPT -2.
