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HP Forum Archive 16

 hp50g - solveMessage #1 Posted by iamnew on 22 Nov 2006, 4:51 p.m. I just have a simple question: Is it possible to solve equations of the type: sqrt(1-x^2)=y by isolating x? If not with the CAS, are there any programs for the hp50g which can do? Thanks for your answers in advance.

 Re: hp50g - solveMessage #2 Posted by Chuck on 22 Nov 2006, 5:53 p.m.,in response to message #1 by iamnew Why certainly. In RPN mode with 'sqrt(1-x^2)=y' on level two, and 'x' on level one, SOLVE returns two solutions {x=-.5sqrt(y^2-4), x=.5sqrt(y^2-4)}

 Re: hp50g - solveMessage #3 Posted by Shu Y Pong on 23 Nov 2006, 12:21 a.m.,in response to message #1 by iamnew Also, if you like, you can use the equation writer, right shift EQW, type in your equation an hit enter, you will then see your equation in the stack, then enter the variable you want to solve for in single quotes, 'x' on the next line. Then left shift 7, S.SLV. You'll get the symbolic solver menu, then hit SOLVE or ISOL. Or SYMB then SOLVE then SOLVE again. Edited: 23 Nov 2006, 2:15 a.m.

 Re: hp50g - solveMessage #4 Posted by iamnew on 23 Nov 2006, 2:46 a.m.,in response to message #3 by Shu Y Pong Thanks - the problem was that in the CAS modes complex wasn't activated. But when I type in: x^2+y^2=x/sqrt(x^2+y^2) and want to isolate y, the answer is: "Not reducible to a rational expression" Is there a solution with the calculator? ( It would be for positive x: y=sqrt(x^(2/3)-x^2) )

 Re: hp50g - solveMessage #5 Posted by Happy HP User on 23 Nov 2006, 5:21 a.m.,in response to message #4 by iamnew In short: no. While the CAS was programmed while using Maple, the HP50 is not Maple. You have discovered a limit of your 50, which is good to know. You now have an idea of just how far you can push the CAS when using Solve. It will solve a large class of equations numerically and symbolically, but not all. For comparision purposes this example chokes the Derive-based TI89 while solving for x but returns a solution for y. As I'm sure you're aware, such problems are best solved with a pc-based program. Of course if your 50's performance is unsatisfactory you're always free to just do the algebra by hand ;-) Edited: 23 Nov 2006, 5:29 a.m.

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