# Define functions with independent variables other than x.

jaredwarner4 shared this question 3 years ago
Answered

I'd like to define a function with an independent variable other than x, so that when I call this function as an object in a text box, the text appears using my specified independent variable. At the moment, whenever I call a function as an object in a text box, the text appears using the default variable x.

Any ideas?

## Comments (5)

1

I tried it in Classic5 & 6 without any problem. Which version of GeoGebra are you using on what kind of device?

chris

1

Thanks for your reply. It makes me realize that I wasn't specific enough in my question. Sorry about that. Let me clarify.

I have an input box that is used to define a function f in terms of x. I then want to display (as text) the function f'(x) evaluated at c (i.e. f'(c)). I can't seem to make your solution apply in this case.

Sorry again for the unclear question. I hope this is better now.

1

To show f'(c) in a text, reffering to f as well to c, create a text box, select in the list of objects the number c. Now a box with c is created. In this box you can change the content of the box from c into f'(c). So you can type, erase etc. in these textboxes, introducing formulas.

1

Thank you again, but again it seems I've been unclear. I'm confident this time my question will finally come through.

In the c_text.ggb file you provided, I want the text to read "2c" instead of "2" as it currently reads. In other words, I don't want to evaluate the function f'(x) at a number for c, I want to evaluate f'(x) at the variable c (replace all x's with c's).

1

Hi

My idea (…) is CAS with substitute command

Then you drag 2c (in the exemple) into graphics, and you have your text

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