Silly question about solver

[mop80087]

Hi,

I have a silly question, sorry...

why when I put in "cas nspire": solver(x^2-2^x=0, x)
i get results x=-0,766... or x=2 or x=4

but in my HP Prime when i put: solver(x^2-2^x=0, x)
i have only one result x=2

Why?

or is there another way to get all the possible results of an equation?

Cumprimentos/Sincères salutations/Cordiali saluti/
Best regards/Mit freundlichen Grüßen/Saludos
Diamantino Valente
Portugal

[Tim Wessman]

The CAS in Prime does not automatically switch to approximate mode (like the Nspire) when it cannot perfectly resolve a solution exactly in a symbolic way. This simple equation actually requires a rather advanced function to represent the result symbolically and this is not yet supported in the CAS on Prime or in the Nspire which is why neither can symbolically solve for all roots.

simply add a "f" to the front to use the "fsolve" command instead. (Stands for "floating point solve")

fsolve(x^2-2^x=0)

[mop80087]

Tim, thanks for the reply...
But, if I'm not mistaken, with fsolver is necessary to place minimum and maximum. Is not so practical but ok...

[Helge Gabert]

No, you don't need to.

fsolve(x^2-2^x, x) returns [-.766... 2. 4.].

[Eddie W. Shore]

Make sure that you are in Radians mode when using fsolve. I get blanks when using fsolve in Degrees mode.

[mop80087]

Thanks Eddie,

You are right Helge...

Why complicate what is easy? that´s my opinion