Find the domain range in this equation under root of 4-x?

Well, It's been a while since I was in Calc, but basicly for the domain, what values of X would make the equation invalid. Since 4-x is under the root/ratical, then 4-x must be greater than 0 or else you end up with an imaginary answer and that's not good. So pretty much, you just have to solve the equation 4-x ( > or equal to) 0. When you solve that you'll get 4 (> or equal to) x. So you end up with a domain of

Dx= (-Infinity , 4]. which basicly says that all values from negative infinity to 4 work as a value of x and is the domain

As far as range is concerned, i don't remember how to find it the technical way, but basicly, for a negative root problem, the range is always

Ry= (-Infinity , Y value of the vertex (in this case 0 since the vertex is on the x axis 4,0)]

I hope that helped but I have a feeling I did a terrible job of explaining. Good luck with your class!