How do we know if a given graph is a FUNCTION. If we know ahead of time what the function is a graph of we can use that information to help us with the graph and if we dont know what the function is ahead of time then all we need to do is plug in some xs compute the value of the function which is really a y value and then plot the points. Graph variations ofycos xand ysin x.
So this graph right over here is essentially a definition of our function.
If the problem wanted you to use the negative root it would say - sqrt x. The basic function is just the function in its natural state. If the problem wanted you to use the negative root it would say - sqrt x. Remember sqrt x tells you to use the principal root which is the positive root.