Hey,

For this problem you must find out the domain of this function first.

Let y=√(x-3) , the value under the root is always positive . So, (x-3) is greater than or equal to 0. Therefore, x is greater than or equal to +3. So domain is [+3, infinity)

Putting the value of x as 3, we get y =0. And putting the value of x as infinite we get y= infinity. So , range is [0, infinity).

Hope this helps.