# Cp Can't Solve This Integral

### #1

Posted 22 July 2007 - 11:07 PM

TI-89 have no problems, but the CP

The result is always the same Integral... try it

### #2

Posted 22 July 2007 - 11:37 PM

### #3

Posted 23 July 2007 - 08:26 AM

So what?

whats your question?

### #4

Posted 23 July 2007 - 10:46 AM

### #5

Posted 23 July 2007 - 10:51 AM

thx

### #6

Posted 23 July 2007 - 04:22 PM

If CP would be able to solve everything, his price would tend to infinity

Bye.

### #7

Posted 23 July 2007 - 05:04 PM

**A CAS system is not your replacer, it should be your helper!**You should try to make it useful your self.

### #8

Posted 24 July 2007 - 02:53 AM

A CAS system is not your replacer, it should be your helper!

You should try to make it useful your self.

Totally agree.. and btw, you're a crack on maths dude, i never guessed that solution

### #9

Posted 24 July 2007 - 07:49 AM

i know that i can solve it by hand...but i would check the result with my CP...

thanks to vanhoa, but i think you have to write |t=(x-1)^0.5 instead of |t=x in the last line....

then you get the right answer

### #10

Posted 24 July 2007 - 12:47 PM

### #11

Posted 02 August 2007 - 03:48 AM

OS 3.02 can solve this integral in complex mode, the result seems to be very complicated.

### #12

Posted 02 August 2007 - 08:24 AM

Try to tell CP that |x|>=1 and see if OS 3.02 can handle it correctly (since |x|>=1, the result should be real, not complex).OS 3.02 can solve this integral in complex mode, the result seems to be very complicated.

Alternatively, use the function IntgSub (I have written that function a long time ago, in order to compute integrals by substitution). Here is the function and here is a step-by-step explanation of it. This function is not perfect, since ClassPad's user-defined functions are very limited by nature, but you will be able to solve integrals by substitution easily (provided, of course, that you can guess a convenient substitution). In this case, type:

IntgSub(<acid111's integral>,x=u^2+1)x=u^2+1 is the obvious convenient substitution here; actually, it can be replaced by x=u^4+1, or any even power of u plus 1. You will get the correct answer easily.

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