The Square of the Root Delima!

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The Square of the Root Delima!

The other day I was sitting in math class, bored as always, when we started
doing some pointless review on f(g(x)) type functions. I knew from previous
experience that the teacher was about 30 seconds away from tricking some poor
sap by saying "if f(x)=x^2 and g(x)=root(x), what is f(g(x))." The idiot
answer is "duhh x", but the correct answer is "duhh x where x >= 0", because
in graphing functions you can't do imaginaries. As he gave the little hint
"warning" about restrictions, I said to myself "yawn, the 85 handles them if
you enter then f(g(x)) in the y= directly". However since the last time I had
tried this I had gotten a TI-92, which happened to be directly infront of me,
so I punched in y1=root(x^2) and hit the graph button. I was totally stunned
to see a graph of y=x staring back at me. I then grabbed my 85 (and my
neighbors 82, which he wasn't very happy about) and did the same thing, only
it graphed y=x where x >= 0.


I thought I had some clue as to what was going on but somebody stole my 92 a
couple days ago and now I can't remember what my hunch was so can somebody
just tell me whats going on... I know there is a problem with paren's where it
will eval root(-5)^2 as root((-5)^2) but shouldn't the 92 not be graphing the
x<0 portion as well?