negative number raised to even power

[jebem]

(04-26-2015 12:47 PM)rprosperi Wrote:  

(04-26-2015 06:38 AM)parisse Wrote:  Could you give a list of softwares/calcs that evaluate -2^2 (algebraic notation) to 4?

HP-20S returns 4
HP-17BII+ returns 4 (Algebraic mode)
HP-10B returns 4

...and so I assume all HP algebraic machines (Pioneers at least) will behave the same way.

I've been following this thread and I remember my school days in the 70's. All my math teachers in two different countries told us that:
a) 2^2 = 2 x 2
b) + and - signals gives -
c) - and - signals gives +
d) so, -2^2 = -2 x -2 = 4
That's the way I've learned.

And the calculator manufacturers of my school time agreed with mt teachers as well.
I had several machines, starting with a Casio fx-21, then a HP-25, then a Texas TI-57, and never got a different answer.

Until now, that is.
The new calculator generations tends to favor the common accepted rules these days and give me a different answer.


Some of my machines that also agrees that: -2^2 = 4
Casio fx-21
Texas TI-58C
Texas Galaxy 67
Texas TI-55II
NOVUS 4510
Sharp EL-8118
ELEKTRONIKA MK-52
HP-25
HP-11C
HP-15C
HP-21S
HP-27S
HP-35S (RPN and ALG modes)
HP-49g+ (RPN and ALG modes)

New fashion machines telling that: -2^2 = -4
Casio fx-730P
Casio fx-4500p
Casio fx-6300p
Casio Algebra FX 2.0 Plus
Texas TI-89
HP-300s+
HP-PRIME (Textbook, Alg, and RPN)