ANSWER
The domain of the function
[tex]y = 3 \sqrt{x} [/tex]
is
[tex]x \geqslant 0[/tex]
EXPLANATION
The domain of a function refers to all values of x for which y is defined.
Since this is a square root function, we need to keep the expression under the square root sign to be greater than or equal to zero.
As soon as the expression under the root sign is less than zero, the function will not be defined.
This means that the square root of a negative number will not be a real number.
Thus the domain is
[tex]x \geqslant 0[/tex]
or
[tex][0, \infty )[/tex]
