Set the radicand in greater than or equal to to find where the expression is defined.
Solve for .
Subtract from both sides of the inequality.
Divide each term by and simplify.
Divide each term in by .
Cancel the common factor of .
Cancel the common factor.
Divide by .
Move the negative in front of the fraction.
The domain is all values of that make the expression defined.
Find the Domain y = square root of 1+9x