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1-Newbie

## Multiple integration Problme

I want to integrate the following expression in mathcad.

the answer should be the following if p(r)=po=constant

But when i try to solve this expression in mathcad i get this:

It should give 64 instead of 24. What am i doing wrong.?

4 REPLIES 4
15-Moonstone
(To:akalim)

Try:

Alan

24-Ruby V
(To:akalim)
 It should give 64 instead of 24. What am i doing wrong.?

Hard to tell without seeing the sheet. And if you attach your sheet, chances are, I am not able to open it, if its not Prime 3.0 or below. Thats the PTC way of usability and compatibility:-(

In the way you typed in your expression, the integrand r*(1/r)*(1/r) simplifies to 1. So the first integral gives you r, the second r^2/2, the third r^3/6 and finally the last one r^4/24. So Mathcad/Prime is correct with its answer.

If you type in the integral(s) you really want to evaluate, you will get the result you expect.

Here is what Mathcad 15 comes up with

When I type in the expression, beginning with the inner integral, the parenthesis are set automatically by Mathcad, but can be deleted manually without any problem, as you can see in the second expression. If you start with the outer integral, the parenthesis are not set at all. That behavior can be different in Prime (I am too lazy to try and wait for  Prime to start up).

23-Emerald II
(To:akalim)

The explanation for your last result is found as follows:

But that isn't what you set out with.

Some food for thought (Mathcad 11):

Success!

Luc

1-Newbie
(To:akalim)

Thanks a lot guys. Its working now.

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