Re: The Square of the Root Delima!
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Well, I just got done with the experiment, and here's what i figure: The
92 can deal with imaginary numbers much better than the 85. if you press
mode, you can choose whether or not to display complex numbers, or just
output an error. when the 92 is evaluating the funciton, it evaluates all
the way until the end of the funcion before displaying. so, when it takes
root(-1), it returns i, and then computes (i)^2, which is indeed -1. it
determins that -1 is a real number and therefore displays it. this isn't a
discrepency, it's just another way of handeling imaginary numbers.
jj
At 03:39 PM 10/19/96 -0700, Richard Steenbergen wrote:
>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?
>
>
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