SOLUTION: one of my problems for a domain and range section was pretty difficult...I'm not sure what part of the problem I got wrong because it wasn't specified. find the domain algebraic

Question 58160: one of my problems for a domain and range section was pretty difficult...I'm not sure what part of the problem I got wrong because it wasn't specified.
find the domain algebraically and the range graphically.

square root of(x^2-2x-8)
> is greater than or equal to since I don't know how to type the sign
here's what I did: x^2-2x-8 > 0
(x-4)(x+2) > 0
x>4 x>-2 and the x can't be negative due to the square root.
Domain: (-infinity, -2] U [4, infinity)
Range: (-infinity, -2] U [4, infinity)
Do I have the domain and range correct?
Answer by hayek(51) (Show Source): You can put this solution on YOUR website!
The domain looks good, but the range of a square root function is from 0 to infinity. I can't tell from the problem whether they intend you to include the negative solution as well, although if so, you don't have a function because it fails to map x to y uniquely.
Here is the graph, although it the line on the right is supposed to go all the way to the x-axis.

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