Error in simplifying a function

[swagner53]

Hi,

In helping my son with some simple algebra homework (he was duly impressed with the Prime), we ran across one problem that would not simplify further (but was correct) and another that simplified incorrectly.

Case 1:

(3) NTHROOT ((4) NTHROOT (64*z^18*w^6))

returns:

(w^6*z^18)^(1/12)*sqrt(2)

which is correct, but I could not find and command to simplify to:

sqrt(w)*z^(3/2)*sqrt(2)

Case 2:

(4) NTHROOT (100*a^2+300*a*b+225*b^2)

returns:

√(-2*a-3*b)*√5

which is incorrect. It should be sqrt(2*a+3*b)*sqrt(5)

I am using the latest release under both the real (revision C) and virtual (PC) calculators. Any ideas?

Thanks and take care, Steve

[Aries]

Just for comparative purposes, here is what the Nspire got (using EXPAND):



Best,

Aries

[parisse]

I have now fixed Giac source code to properly simplify case 2 under the assumptions assume(a>0); assume(b>0).
I'm also adding support in expand to expand a product to a power.
I have no idea of the delay to get this fix and improvement into the HP Prime firmware.