CAS: 0/0 is undefined, however 1/0 is infinite?

[Joe Horn]

(10-21-2018 10:39 AM)sasa Wrote:  Sorry Tim, I'm not going to read any article which try to "prove" obvious nonsense, as here that 1/0=inf.

Why ask a question if you have already convinced yourself that every reply is "obvious nonsense"?

Quote:As mentioned already, in special cases/theory it may be perfectly correct, however that does not mean it should be generalized on plain real numbers, which is absolute nonsense.

CAS is NOT "generalized on plain real numbers". But Home is. Try 1/0 and 0/0 in Home.

If you want CAS math to be limited to something other than the Reimann Sphere of numbers (in which 1/0=infinity and 0/0 is undefined), then you have to tell it so.

Quote:I would like to see teacher who explain to students why 1/0 is infinity, since a calculator return such result...

Me! Me! <waves hand enthusiastically> Your problem is that you never had me as your math teacher.

1/0 equals infinity not because a calculator says so, nor does the HP Prime (and HP 50g) say so because it is "true", but because it is USEFUL. Is Euclidean Geometry TRUE and are non-Euclidean geometries "absolute nonsense"? No. They are both nothing more than useful tools for certain tasks. Saying that 1/0=infinity is absolute nonsense is like saying that Phillips screwdrivers are designed wrong because they can't turn flathead screws. Prime's CAS is a tool which works by default in the Reimann sphere of numbers. Use it that way. If you want to work in some other number space, either tell it so, or stick to Home view (in which you can enable or disable complex results).