marking the break visually in the graph in a non-continous function?

Stefan shared this question 3 years ago

Answered

(x^2+x-2)/(x-1)

I have to graph some functions that like this one are non-continuous.

Now, Geogebra plots this all fine, but in the math book (and probably in the results I have to send in) they would like me to mark the break point with arrowheads on the function line. So that two arrowheads oppose each other and the tips are the break point in the function.

I know where the point is, when calculating ex. f(1) it returns "undefined" and it obviously doesn't want to set a point A there ;)

Is this possible to do in Geogebra? I have not found a setting in the function settings that allows me to do it. I have found a "line style setting" where I can select different arrowheads but this seems not to be a solution to my problem.

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Comments (3)

rami ● 3 years ago

Maybe the solution in the attachment is good enough.

variants:

In some cases a "+" or "x" can be better as a point representation instead of the "o".

Files: holeMark01.ggb

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Stefan ● 3 years ago

Yes, setting a point there manually will work for me. I gather that Geogebra cannot do this automatically then. Thank you :)

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M_OLoughlin ● 3 years ago

Here are two suggestions. The function simplifies to $$f(x)=x+2$$ for $$x \neq 1$$ so:

Plot the function as a piecewise function, one portion for $$x<1$$, the other for $$x>1$$.
Construct two vectors pointing inwards towards the discontinuity.

Second suggestion:

Plot two separate piecewise functions, one for $$x<1$$, the other for $$x>1$$.
Colour the functions differently. Where the colour changes is the discontinuity.

Files: discontinuity_v... discontinuity_c...

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