# Creating a System of Inequalities Graph from Two Math Inputs

**URL:** <https://cl.desmos.com/t/creating-a-system-of-inequalities-graph-from-two-math-inputs/4486>\
**Category:** Questions\
**Tags:** simplefunction\
**Created:** [September 29, 2022, 3:30pm UTC](https://cl.desmos.com/t/creating-a-system-of-inequalities-graph-from-two-math-inputs/4486 "2022-09-29T15:30:37Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![William\_Pomfret](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/william_pomfret/32/3842_2.png) [@William\_Pomfret](https://cl.desmos.com/u/William_Pomfret)\
**Post date:** [September 29, 2022, 3:30pm UTC](https://cl.desmos.com/t/creating-a-system-of-inequalities-graph-from-two-math-inputs/4486/1 "2022-09-29T15:30:38Z")

</div>

I am trying to create an activity that allows students to examine a graph of a system of linear inequalities and write the corresponding inequalities in Math Input boxes. Once the students have written their inputs, I would like to be able to render a graph from those input boxes that allow the students to compare the graphs of their inequalities to the original graph. I have tried using the simpleFunction tag to complete the task, but it does not simple to work for inequalities. I have pasted the activity below. If anyone can please help with this process, I would greatly appreciate it.

> **[X Marks the Spot • Activity by William Pomfret (Cajon HS)](https://classroom.amplify.com/activity/6334cddf1a710b7a4742fa76)**
>
> Instructions:
> • Complete the Get It Started on Google Forms.
> • Complete the X Marks the Spot assignment on Desmos.
> • Once you have completed the assignment, complete the Before You Go survey.
> • When you complete the assignment, click “Mark as Done”...

---

<div class="post-metadata">

**Author:** ![pirsquared](https://avatars.discourse-cdn.com/v4/letter/p/4af34b/32.png) [@pirsquared](https://cl.desmos.com/u/pirsquared)\
**Post date:** [September 29, 2022, 7:43pm UTC](https://cl.desmos.com/t/creating-a-system-of-inequalities-graph-from-two-math-inputs/4486/2 "2022-09-29T19:43:59Z")

</div>

In the graph itself, you can have `f(x,y)>0` (you might also want to set up `f(x,y)=y-x` or similar, so you can style the inequality to your liking.

Then in the CL, you need:  
`function("f"): parseInequality(Inequality1.latex).differenceFunction(`x`,`y`)`

In essence, this takes `y>-4x-1` from the students’ input, creates the function `f(x,y)=y-(-4x-1)`, then plots `y-(-4x-1)>0`.

---

<div class="post-metadata">

**Author:** ![William\_Pomfret](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/william_pomfret/32/3842_2.png) [@William\_Pomfret](https://cl.desmos.com/u/William_Pomfret)\
**Post date:** [September 29, 2022, 8:51pm UTC](https://cl.desmos.com/t/creating-a-system-of-inequalities-graph-from-two-math-inputs/4486/3 "2022-09-29T20:51:30Z")

</div>

Thank you so much. This worked well. The only issue I have now is that when I did the two parseInequality lines, the submit button disappeared. The Submit button was the controller for all of my hidden objects. Do you know how to fix this?

---

<div class="post-metadata">

**Author:** ![pirsquared](https://avatars.discourse-cdn.com/v4/letter/p/4af34b/32.png) [@pirsquared](https://cl.desmos.com/u/pirsquared)\
**Post date:** [September 29, 2022, 9:05pm UTC](https://cl.desmos.com/t/creating-a-system-of-inequalities-graph-from-two-math-inputs/4486/4 "2022-09-29T21:05:37Z")

</div>

No idea why your changes should have affected that - however, you can always force the showing of a Submit button by including `showSubmitButton: true` in the CL for the Inequality2 Math Input