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From: Bjoern Schliessmann on 4 Dec 2007 18:56
Hello,

Apart from the rest of my course (using TI Voyage 200 ;) ), I'm
using an HP 50g (2.09) for a few weeks now and I like it a lot. I
noticed two things I could neither explain to me nor find anything
about it in the group archives though; so I hope you could have
some hints.

Firstly, I tried to solve a simple quadratic equation like this (no
complex mode, no approximate mode):

x^2 = 2-sqrt(2)

("sqrt" is the square root)

SOLVEVX returns an empty set. But there is a real solution, isn't
there? If I turn on complex mode or approximate mode, the expected
(real!) solutions are printed. Why is that so -- some obscure
mathematics I didn't consider, or a CAS problem?

Secondly, please consider this example:

sqrt(2-sqrt(2))

"simplifies" (using EVAL) to

(-1+SQRT(2)) * SQRT(SQRT(2) * (1+SQRT(2))) .

What kind of "simplification" :) is this, i. e. which rules make the
CAS create such an expression from a simple root of a sum? And how
can I make the way back to the simple form, if any? (I tried a lot
of manipulation functions but didn't succeed yet.)

Regards,


Bj�rn

--
BOFH excuse #126:

it has Intel Inside

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