Find the The domain of the function of

1/sqrt(9x+3)

my answer after solving was [-2/3, infinity)
When i asked for help my teacher gave me this cryptic response: "what has to be true of expressions in the denominator? Combine these ideas and your will get your answer!"
I have no idea what she is talking about. Please help me.

Question

Find the The domain of the function  of

1/sqrt(9x+3)

my answer after solving was [-2/3, infinity) 
When i asked for help my teacher gave me this cryptic response: "what has to be true of expressions in the denominator?  Combine these ideas and your will get your answer!" 
I have no idea what she is talking about. Please help me.

anonymous · Answer

this is a rational function, what makes a rational function DNE?

i have absolutely no idea how you arrived at [-2/3, infinity]

anonymous · Answer

9x + 3 = 0, x = -3/9 = -1/3

anonymous · Answer

because it has to be in interval notation. so the set up would be 9x+3is greater than or equal to 0, and i solved based upon that which gave me -2/3, so the interval would be [-2/3,infinity) because the number is given it has to have the [ sign for the number .
the problem is actuall 1/sqrt9x+2 ...not 9x+3, i wrote it wrong on here

anonymous · Answer

What does DNE mean?