# Cp 300 Is Not Able To Solve This Differential Equation

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### #1 acid111

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Posted 14 May 2007 - 06:15 PM

Hi, new day, new problem

my cp shall solve this d-equation:

y'*(x+1)+x*(y-1)=0

the result from the cp is: y'(x+1)=xy+y , what's that ?

mmmh...

the right solution is: y= ((x+1)*C1) / (e^(x)) + 1
(TI-89 is able to solve this)

bug ?

### #2 Colombia

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Posted 14 May 2007 - 07:21 PM

Mu CP 300 is able to solve this differential equation.

It show me {y=x.e^(-x).const(1)+e^(-x).const(1)+1}

CP can do it, maybe you can match with the CP300.

Please don`t compared the casio with the texas or another calculator.

If you don`t know how to uses something on the CP300 just ask, don`t say because the ....... can do it.

### #3 acid111

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Posted 14 May 2007 - 08:29 PM

tell me how to calculate this equation in cp...

here is a screenshot, i have took it from cp-manager 2.20.
but i have the same result on my cp mit ver.3.01:

???

### #4 Kilburn

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Posted 14 May 2007 - 09:32 PM

Try to set it on Real mode, not Complex. It sometimes work.

### #5 SoftCalc

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Posted 15 May 2007 - 12:20 AM

tell me how to calculate this equation in cp...

here is a screenshot, i have took it from cp-manager 2.20.
but i have the same result on my cp mit ver.3.01:

???

I'm not quite sure why it isn't working. it works fine on my ClassPad both in real and complex modes. Your screen capture doesn't show the full argument list. What is the full command line? Not that this should effect the result, but do you have anything stored in 'x' or 'y'?

I'm not quite sure why it isn't working. it works fine on my ClassPad both in real and complex modes. Your screen capture doesn't show the full argument list. What is the full command line? Not that this should effect the result, but do you have anything stored in 'x' or 'y'?

Interesting, it looks like you need an explicit * after y'.

### #6 acid111

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Posted 15 May 2007 - 04:54 AM

Interesting, it looks like you need an explicit * after y'.

hmm, yes, the CP needs an explicit * after y' . Now, i see the right solution... very strange

thx

### #7 PAP

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Posted 15 May 2007 - 02:36 PM

hmm, yes, the CP needs an explicit * after y' . Now, i see the right solution... very strange

Hmm, I'm not surprised too much. y(x+1) doesn't need the explicit * because y (in bold italics) is designed just for that (a "stand-alone" variable). However, y'(x+1) does need to be written as y'*(x+1) because y is followed by an operator, and y' is not treated as a "stand-alone" variable. I personally never use bold italics variable names; of course, they are easier to type (especially for x, y, and z), but they look ugly to me and they have problems such as this one.

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