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UnRelatedBurner@sh.itjust.works ⁨8⁩ ⁨months⁩ ago

Uhm, actually 🤓☝️!

Afaik sqrt only returns positive numbers, but if you’re searching for X you should do more logic, as both -3 and 3 squared is 9, but sqrt(9) is just 3.

If I’m wrong please correct me, caz I don’t really know how to properly write this down in a proof, so I might be wrong here. :p
(ps: I fact checked with wolfram, but I still donno how to split the equation formally)

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criitz@reddthat.com ⁨8⁩ ⁨months⁩ ago
You’re correct. The square root operator only returns the principal root (basically, the positive one).

So if x ^2^ = 9 then x = ±√9 = ±3

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- UnRelatedBurner@sh.itjust.works ⁨8⁩ ⁨months⁩ ago
  Thanks, I haven’t connected the dots to that (±) sign and this problem.
  
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- Routhinator@startrek.website ⁨8⁩ ⁨months⁩ ago
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  So I checked this on my smartphone first, and thought maybe the software is just shit… So then I checked it on a Casio scientific calc, and both agree.
  
  -3^2 = -9… And 9 != -9
  
  … Are all the calculators somehow wrong? What’s the math rule I’m forgetting here…
  
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  - criitz@reddthat.com ⁨8⁩ ⁨months⁩ ago
    I think your calculator is interpreting that as -(3^2) and not (-3)^2
    
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    Routhinator@startrek.website ⁨8⁩ ⁨months⁩ ago
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    Oh derp. Yep it is.
    
    Was better when calcs had a +/- button.
    
    And I remembered the math rule too.
    
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h3ndrik@feddit.de ⁨8⁩ ⁨months⁩ ago
|x| = sqrt(…)

would be correct.

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- UnRelatedBurner@sh.itjust.works ⁨8⁩ ⁨months⁩ ago
  Cool! Makes sense to me. Honestly, I’ve never done it this way, but it’s so clean. Love it. Thanks.
  
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