# Symbolics islinear issue

**URL:** <https://discourse.julialang.org/t/symbolics-islinear-issue/123423>\
**Category:** General Usage\
**Tags:** question\
**Created:** [December 3, 2024, 7:21pm UTC](https://discourse.julialang.org/t/symbolics-islinear-issue/123423 "2024-12-03T19:21:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![jcbritobr](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jcbritobr/32/219275_2.png) [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Post date:** [December 3, 2024, 7:21pm UTC](https://discourse.julialang.org/t/symbolics-islinear-issue/123423/1 "2024-12-03T19:21:01Z")

</div>

Why the equation below is triggering islinear assertion if the equation is linear?

```julia
julia> f = 2x -4 == 0
(-4 + 2x) == 0
julia> symbolic_linear_solve(f, x)

```

```julia
ERROR: AssertionError: islinear
Stacktrace:
 [1] symbolic_linear_solve(eq::Num, var::Num; simplify::Bool, check::Bool)
   @ Symbolics C:\Users\jcbri\.julia\packages\Symbolics\YbNrd\src\linear_algebra.jl:105
 [2] symbolic_linear_solve(eq::Num, var::Num)
   @ Symbolics C:\Users\jcbri\.julia\packages\Symbolics\YbNrd\src\linear_algebra.jl:101
 [3] top-level scope
   @ REPL[34]:1

```

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<div class="post-metadata">

**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [December 3, 2024, 8:59pm UTC](https://discourse.julialang.org/t/symbolics-islinear-issue/123423/2 "2024-12-03T20:59:29Z")

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`(-4 + 2x) ~ 0`?

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<div class="post-metadata">

**Author:** ![jcbritobr](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jcbritobr/32/219275_2.png) [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Post date:** [December 3, 2024, 10:18pm UTC](https://discourse.julialang.org/t/symbolics-islinear-issue/123423/3 "2024-12-03T22:18:12Z")

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> [@jcbritobr](#):
>
> `2x -4 == 0`

Im sorry, but I’m not understanding the assertion. Islinear is telling me that a first degree equation is not linear?

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<div class="post-metadata">

**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [December 3, 2024, 10:22pm UTC](https://discourse.julialang.org/t/symbolics-islinear-issue/123423/4 "2024-12-03T22:22:09Z")

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No, that’s not a first degree equation. It’s a function with a boolean operation, not an equation.

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<div class="post-metadata">

**Author:** ![jcbritobr](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jcbritobr/32/219275_2.png) [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Post date:** [December 3, 2024, 10:30pm UTC](https://discourse.julialang.org/t/symbolics-islinear-issue/123423/5 "2024-12-03T22:30:10Z")

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Oh, thank you.