Question 58160
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.
{{{graph(300,200,-10,10,-10,10,sqrt(x^2-2x-8))}}}