# Discrepancy between Geogrebra, Excel, Desmos, and TI-83 PLUS...what's the deal?

#### nddn

##### New Member
As my title implies, there is a discrepancy between Geogebra, Excel, Desmos, and TI-83 Plus. Let me explain myself

I have created a fifth and sixth power regression model through excel to fit two sets of data respectively. Now, I want to calculate the derivatives for both sets of data using my polynomial model. When I go to graph the fifth degree polynomial, all I get on Desmos, Geogebra, and my TI-83 Plus is a vertical line as though the relationship of the data is undefined. On Excel, a rather nice curve comes as the equation of the line.

How do I resolve this and what does this mean? A response will be hugely appreciated and needed.

#### Dason

I don't really understand what you did. And the information you provided doesn't seem to be nearly enough to solve whatever issue you're having.

#### nddn

##### New Member
@Dason

I collected a set of data points. I entered them on Excel.

I used those points (x,y) to create a scatter plot and from there, a trend curve. That gave me an equation that is 5th degree for one data set and for another data set.

I wanted to measure the rate of change but I needed to graph the regression equation given to me by excel, which was a 5th degree polynomial as I mentioned earlier. When I went to graph it on Desmos, Geogebra, and my calculator, a single vertical line was graphed by this fifth degree polynomial. When I graphed it on Excel, a normal fifth degree curve showed up.

My question is why does the same equation (5th degree) act as a curve in Excel and an undefined line in Desmos, Geogebra, and my calculator. I can't disclose the equation on the Internet because it's for a project.

I think you should have enough information and my question should make sense now that I've clarified things. P