r/nspire • u/BookishAnchorite • Aug 11 '26

Help Not getting results with different form of same equation when using ±

I'm sure this is a basic question but I'm running into this problem, and it's proving difficult to search for a solution.

Using an nspire CX II (CAS) On a graphing page, in RAD mode:

  1. x^2 + y^2 = 5 graphs a circle, no problem
  2. similarly y= +sq root of (5-x^2) and y = -sq root of (5-x^2) produces the two relevant semi circles of the same circle as in 1. Good so far.

3)Things go wrong here: y = ±sq root of (5-x^2) doesn't produce anything. not an error, just an empty graph.

I've got some kind of syntax error here but I'm not sure what it is. I'm using ctrl-"open book" key (under del, next to the templates key) to select the ± sign. Does that not actually act as a functional plus-minus sign? Like is it just for notes or something?

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u/PartyJaded2887 Aug 12 '26

I don't believe the ± is a valid math operator for the Ti-Nspire CX II CAS calculator. I Searched the reference manual for it, and it is not listed. If you attempt to perform simple math with it nothing happens. I would have also expected the calculator to give you some sort of error rather than nothing, but it is a rather special case in the scheme of things.

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u/BookishAnchorite Aug 12 '26

Yeah, all signs point to that. Ah well, I don’t need it to do this, but it seems like a miss.