# Restrict input to first order inequality

**URL:** <https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300>\
**Category:** Questions\
**Created:** [May 17, 2022, 1:55am UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300 "2022-05-17T01:55:48Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Jeff\_Holcomb](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/jeff_holcomb/32/433_2.png) [@Jeff\_Holcomb](https://cl.desmos.com/u/Jeff_Holcomb)\
**Post date:** [May 17, 2022, 1:55am UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300/1 "2022-05-17T01:55:48Z")

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I am modifying the “Point Collector: Lines” activity a bit. I am wanting to restrict the input to be only non-compound first degree inequalities, ex: y≤x+2

I was using it with students today and those clever students started entering all sorts of cool inequalities to collect points! Yes, cool indeed, but my intention for the lesson was to focus on the more mundane, for now. Ideas?

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**Author:** ![Daniel\_Grubbs](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/daniel_grubbs/32/719_2.png) [@Daniel\_Grubbs](https://cl.desmos.com/u/Daniel_Grubbs)\
**Post date:** [May 17, 2022, 2:04am UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300/2 "2022-05-17T02:04:27Z")

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```auto
isLinear= isDefined( xyLine( parseInequality(this.latex).differenceFunction("x","y") ) )

```

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<div class="post-metadata">

**Author:** ![Jeff\_Holcomb](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/jeff_holcomb/32/433_2.png) [@Jeff\_Holcomb](https://cl.desmos.com/u/Jeff_Holcomb)\
**Post date:** [May 17, 2022, 2:50am UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300/3 "2022-05-17T02:50:56Z")

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[quote=“Daniel\_Grubbs, post:2, topic:4300”`isLinear= isDefined( xyLine( parseInequality(this.latex).differenceFunction("x","y") ) )`  
[/quote]

I got an error "Function body and identifiers must be strong or latex. I got [[Object,Object]]

And TY

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<div class="post-metadata">

**Author:** ![Jeff\_Holcomb](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/jeff_holcomb/32/433_2.png) [@Jeff\_Holcomb](https://cl.desmos.com/u/Jeff_Holcomb)\
**Post date:** [May 17, 2022, 2:57am UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300/4 "2022-05-17T02:57:58Z")

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This seems to work:  
LHS = parseInequality(w2input.latex).lhs  
RHS = parseInequality(w2input.latex).rhs  
EQ = “{LHS}={RHS}”  
check1 = when isDefined(xyLine(EQ)) “Line” otherwise “Not Line”

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<div class="post-metadata">

**Author:** ![Jeff\_Holcomb](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/jeff_holcomb/32/433_2.png) [@Jeff\_Holcomb](https://cl.desmos.com/u/Jeff_Holcomb)\
**Post date:** [May 17, 2022, 3:00am UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300/5 "2022-05-17T03:00:11Z")

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Got some weird formatting when I pasted that code in. Let’s see if this works:  
Eq = “{LHS}={RHS}”

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<div class="post-metadata">

**Author:** ![Jeff\_Holcomb](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/jeff_holcomb/32/433_2.png) [@Jeff\_Holcomb](https://cl.desmos.com/u/Jeff_Holcomb)\
**Post date:** [May 17, 2022, 3:01am UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300/6 "2022-05-17T03:01:31Z")

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Nope! Should be “dollar\_sign{LHS}=dollar\_sign{RHS}”

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<div class="post-metadata">

**Author:** ![Daniel\_Grubbs](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/daniel_grubbs/32/719_2.png) [@Daniel\_Grubbs](https://cl.desmos.com/u/Daniel_Grubbs)\
**Post date:** [May 17, 2022, 4:55pm UTC](https://cl.desmos.com/t/restrict-input-to-first-order-inequality/4300/7 "2022-05-17T16:55:31Z")

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Use triple backticks on the line above and below your code in the forum to keep formatting.