Set the radicand in greater than or equal to to find where the expression is defined.

Add to 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 .

Divide by .

The domain is all values of that make the expression defined.

Interval Notation:

Set-Builder Notation:

Find the Domain y = square root of 3x-21