# Graphing Calculator

I’d like to use the full screen graphing calculator in an assessment activity. The students need to graph three lines. They can do C=40d+300 and C=75d+200, which are the two other curves in the assessment just fine. They also need to be able to graph a horizontal line C=500. It won’t work unless they use y=500. C=0d+500 works for the horizontal, but I’d rather not. Any help much appreciated.

Many thanks
Ingrid

C(d)=500 also works, but otherwise there’s no real way for Desmos to know that you intend C to be a function rather than a constant.

You could probably make a folder, click hide from students, and in the folder have y = c. Outside the folder have an initial equation like c = 0, which they have to change.

Yeah, I was thinking along those lines too initially - but the only issue there is that you cannot then define any further functions in C or else you get the “defined in more than one place” issue.

Oh yeah, good point. If this was done in a graphing component instead it could be achieved.

Thanks guys.

We can’t do it in the graphing component, which is the problem. Might just have to let them get away with y=500 or C=0d+500.

Any chance that we’ll be able to do something like C=500, along with other functions in C, in the future?

Many thanks
Ingrid

You could have it work without a full screen graph using multiple inputs and simpleFunctions in terms of d.
Current slide 1:

It’s definitely a thought for next year. At the moment, the kids need to be able to set up the axes themselves as part of the assessment. But I figured out that if they just restrict the domain straight away, it graphs as it should.

Thanks both of you for all of your help and suggestions. Everything is much appreciated and just gives me food for thought for the next activity.

I edited and took the restrictions out of the graph. They can enter restrictions in the inputs and they will graph accordingly. Range restrictions won’t work though.