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HP Forum Archive 06

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HP 49G HELP!!!!
Message #1 Posted by JAIME RUVALCABA on 3 Oct 2001, 6:16 p.m.

HI, WHY CAN'T I FACTOR? FOR EXAMPLE I WANT TO FACTOR 2X^3+5X^2-8X-20 I HIT RED ARROW ALG THEN GO TO FACTOR ENTER THEN GO THE TO EQW WRITE THE EQUATION ENTER AND ENTER IT GIVES ME NEGATIVE 17.556 AS AN ANSWER WHY THE ANSWER IS (X+2)(2X+5)(X-2) I DO IT EXACTLY LIKE THE MANUAL PAGE 5-13 SAYS CAN SOMEONE HELP? JAIME R

      
Re: HP 49G HELP!!!!
Message #2 Posted by Tony Duell (UK) on 3 Oct 2001, 6:51 p.m.,
in response to message #1 by JAIME RUVALCABA

Well, it works for me on my HP49G. I would guess you have a variable called 'X' somewhere in the current path (possibly in the current directory) that contains a numeric value. The HP49G is substituting that value into your polynomial and producing a numeric result before it tries to factorise it. Press the VAR key and see if there's a variable called X in the list. Press NXT if necessary to look at all the variables in that directory. Once you've found it, purge it if you don't need the value any more. Then try the example again.

            
Re: HP 49G HELP!!!!
Message #3 Posted by Erwin on 4 Oct 2001, 5:01 a.m.,
in response to message #2 by Tony Duell (UK)

Hello,

When i have a variable in the current directory, say 'X', And i have a polynomial on the stack (with var. 'X') and press 'factor', the calculator opens a window asking 'Purge current variable'. You can choose either yes, purging it and factors the polinomial, or no. When no is chosen it say's "! FACTOR Error:Mode switch cancelled" , and the operation is cancelled. What flag must be altered so that when i choose 'NO' it will numerically solve the polynomial?

Regards, Erwin

      
Re: HP 49G HELP!!!!
Message #4 Posted by Vieira, Luiz C. (Brazil) on 4 Oct 2001, 8:21 a.m.,
in response to message #1 by JAIME RUVALCABA

Hello;

Not to be widely affirmed, but one must consider that there is always a hidden ´X´ variable when this comes to happen. I once had big troubles when I decided to use a variable which name was associated with a library object; I did not remember that. Mam, I had to delete each reference to the variable after removing the library, cause the variable name was substituted for the XLIB number. Big mass.

Anyway, just to complete Mr. Duel´s answer, if you are in a directory, the so called ´X´ variable will cause this trouble if it is located in any upper directory till Home; say, if you are located in the path

HOME - WORK - MINE

the ´X´ variable may be located in any of them and it might be removed in all occurrences.

(Jaime; where are you?)

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