Why can't I get two solutions from quadratics?

Jan Jansson shared this question 7 months ago
Answered

I teach science and it would be useful to see both (or all) numerical answers with one click in CAS. Sometimes I get them. Sometimes I don't. Sometimes GG adds x=1 on the line and shows just one answer. Sometimes it doesn't. I've been trying to use the command NSolve different ways and the buttons too. I just can't find a logic here.


Could anyone help me? What should I do to see both numerical answers for a quadratic?

Comments (2)

photo
1

Please post your .ggb file

These seem to work OK for me:

Solve(4.5*10^4=((0.00499+x)*x)/(0.0501-x))
NSolve(4.5*10^4=((0.00499+x)*x)/(0.0501-x))
NSolve(4.5*10^4=((0.00499+x)*x)/(0.0501-x),x=1)
Note that if you specify a starting point (ie x=1) then you will get just one solution. Also you can try Solve() in Numeric mode rather than NSolve()

photo
1

If I enter only the equation without a command in text and press the NSolve -button, GG adds x=1 on the line and I get only one answer.

If I use only ( and ) after the NSolve command, like Michael did, I seem to get two numeric answers every time.

So the problem is probably using [ ] and { }. They give me only one numeric answer (and GG doesn't add x=1 on the line).


If I enter Solve(4.5*10^4=((0.00499+x)*x)/(0.0501-x)) and then click the "numeric/almost equals" -button, then I get two numeric answers too but this is a bit confusing...


But okay. Have to just put in the commands with ( and ) then I guess. Thank you!

© 2018 International GeoGebra Institute