Question 693940
You can't divide by zero, so the denominator can't be zero. If it was, then


3x+9 = 0


3x = -9


x = -3


So you have to kick this value out of the domain.


Domain: <img src="http://latex.codecogs.com/gif.latex?\{x|x\in\mathbb{R}, x\neq -3\}" title="\{x|x\in\mathbb{R}, x\neq -3\}" />