Re: The Square of the Root Delima!
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On both my TI92 and TI85 the graph of y1=3Droot(x^2) both graph as =
y1=3Dplus or minus x where y >=3D 0. (i.e. y1 =3D abs(x) which is a "V" =
shape) not as y=3Dx. You must remember that any positive or negative =
number when squared gives a positive result, so when you take the root =
of a number the possible result can be positive or negative and still be =
correct.
example: (-2^2) =3D 4, 2^2 =3D 4, root(4) =3D 2 or -2
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From: Richard Steenbergen[SMTP:buglord@EASYWAY.COM]
Sent: Saturday, October 19, 1996 5:39 PM
To: CALC-TI@LISTS.PPP.TI.COM
Subject: 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)=3Dx^2 and g(x)=3Droot(x), what is f(g(x))." The =
idiot
answer is "duhh x", but the correct answer is "duhh x where x >=3D 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=3D 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=3Droot(x^2) and hit the graph button. I was totally =
stunned
to see a graph of y=3Dx 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=3Dx where x >=3D 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?
References: