# Checking correctness of an inequality in two variables in table

**URL:** <https://cl.desmos.com/t/checking-correctness-of-an-inequality-in-two-variables-in-table/434>\
**Category:** Questions\
**Tags:** validation, correctness\
**Created:** [April 4, 2019, 3:01am UTC](https://cl.desmos.com/t/checking-correctness-of-an-inequality-in-two-variables-in-table/434 "2019-04-04T03:01:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Monark\_Trivedi1](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/monark_trivedi1/32/233_2.png) [@Monark\_Trivedi1](https://cl.desmos.com/u/Monark_Trivedi1)\
**Post date:** [April 4, 2019, 3:01am UTC](https://cl.desmos.com/t/checking-correctness-of-an-inequality-in-two-variables-in-table/434/1 "2019-04-04T03:01:10Z")

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How to check the correctness of an inequality in two variables entered by a student in a table?

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<div class="post-metadata">

**Author:** ![HumanizedMath](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/humanizedmath/32/2947_2.png) [@HumanizedMath](https://cl.desmos.com/u/HumanizedMath)\
**Post date:** [April 5, 2019, 1:14am UTC](https://cl.desmos.com/t/checking-correctness-of-an-inequality-in-two-variables-in-table/434/2 "2019-04-05T01:14:00Z")

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There are a few ways of doing this when it’s an equation, not an inequality.  
a) parseEquation and use lhs rhs  
b) parseEquation and difference functon  
c) use a two variable function and check with a list

However, with an inequality these methods don’t work. I haven’t built one myself, but I imagine you would need to use parse and look for specific values in the latex that students are entering in the table. I hope this helps.

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<div class="post-metadata">

**Author:** ![HumanizedMath](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/humanizedmath/32/2947_2.png) [@HumanizedMath](https://cl.desmos.com/u/HumanizedMath)\
**Post date:** [May 4, 2020, 2:54am UTC](https://cl.desmos.com/t/checking-correctness-of-an-inequality-in-two-variables-in-table/434/4 "2020-05-04T02:54:14Z")

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In the graph component:

```auto
f9a=parseEquation(Table.cellContent(9,2)).lhs
f9b=parseEquation(Table.cellContent(9,2)).rhs
function("f_9"): simpleFunction(f9a,"x","y")

```

Takes students equation of an ellipse and makes it into a function that I check with in the graph:  
 ![image](https://canada1.discourse-cdn.com/flex031/uploads/desmos/original/1X/57960aeb004d75808180c863cedde1a322933a08.png)

It’s slide 7 in this AB:

> **[Unit 2 Conic Sections Review • Activity Builder by Desmos](https://teacher.desmos.com/activitybuilder/custom/5beae78ff822560c6e065d1d)**
>
> Review over conic sections. This includes notes, interactive graphs, and random problem generators.

But it may be hard to follow. There is a lot going on in this activity beause it is an infinite problem set with like 6 different problem types. It might be easier for you to share whatever it is you are working on.

Hope this helps.