Using plus-minus sign in functions

Espron24 shared this question 5 years ago
Answered

Hi,


I was wondering why Geogebra won't let me create a function such as f(x)=±1, f(x)=10^±1 or anything containing the plus-minus sign. It simply says "Invalid input". Is Geogebra just not able to create functions including plus-minus signs yet, or is it simply not possible to create a function using a plus-minus sign in general? If someone knows the answer to this, I would be very helpful if you could explain why this is :)


Posted by Espen Rong

Comments (6)

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Functions can have only one output by definition, so ± is not allowed:

https://en.wikipedia.org/wi...)


Try eg

    Curve[t^2, t^3, t, -5, 5]

and

    x^3+y^2=1


to plot non-functions

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Thank you very much for your answer :)


I was also wondering about another thing: What about equations? For example, if i wanted to solve the two equations (related to my chemistry class) 10=(0.2+x*0.5)/(0.01-x*0.5) and 1/10=(0.2+x*0.5)/(0.01-x*0.5), shouldn't I be able to write 10^±1=(0.2+x*0.5)/(0.01-x*0.5) in Geogebra and get two answers instead of solving the two equations seperately? If not, why?

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"Using plus-minus sign in functions" is a contradiction in itself. A function is characterized in that associated with each x-value is exactly one y-value (and not two different ones).

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In mathematics it is, but in a graphing calculator its an incredibly useful feature that prevents the user from unnecessarily retyping equations several times to get a simple plot.

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In GeoGebra, equations have to be of the form

    function = function

to make things consistent throughout

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hello

no comments

i know conic is not a function but i'd like to use c(0.5) or {c(0.5)}

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