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  •  » Really Difficult Differentiation! Help please!

#26 2012-11-28 02:16:14

BarandaMan
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Re: Really Difficult Differentiation! Help please!

bobbym wrote:

Hi;

Can you differentiate this wrt Pi?



It is just a power rule.

So I think this would become nWYP^n-1Pi^-n+1?

Can we write that in a nicer way?

#27 2012-11-28 06:54:00

bobbym
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Re: Really Difficult Differentiation! Help please!

Hi;

That is not correct but it is close. After we move all the constants to the left you are differentiating:



Please differentiate that right now.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#28 2012-11-28 06:56:50

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

bobbym wrote:

Hi;

That is not correct but it is close. After we move all the constants to the left you are differentiating:



Please differentiate that right now.

That is I think -nPi^-n+1?

#29 2012-11-28 07:00:14

bobbym
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Re: Really Difficult Differentiation! Help please!

Please use brackets.

What is the power rule?



Differentiate that please.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#30 2012-11-28 07:02:15

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

bobbym wrote:

Please use brackets.

What is the power rule?



Differentiate that please.

Sorry: (-n)(Pi)^(-n+1)

Erm I do not know, I think that is just simply 2x once differentiated? Multiply across then subtract the one?

#31 2012-11-28 07:08:36

bobbym
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Re: Really Difficult Differentiation! Help please!

(-n)(Pi)^(-n+1)

That is not correct. Just follow the formula.

Power rule:


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#32 2012-11-28 08:43:09

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

bobbym wrote:

(-n)(Pi)^(-n+1)

That is not correct. Just follow the formula.

Power rule:

Ok, thank you.

Is that not what I did with x^2? Differentiate it and you get 2x? because 2x^(2-1) = 2x^1 = 2x?

#33 2012-11-28 08:58:05

bobbym
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Re: Really Difficult Differentiation! Help please!

Yes, you were right for x^2 but wrong for Pi^(-n) which means you are not using the power rule or you are using it incorrectly.

Now, please differentiate this using the power rule:


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#34 2012-11-28 13:53:24

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

bobbym wrote:

Yes, you were right for x^2 but wrong for Pi^(-n) which means you are not using the power rule or you are using it incorrectly.

Now, please differentiate this using the power rule:

AHHHH! I get this, I think! So it is -nPi^(-n-1) and before I was adding one!?

#35 2012-11-28 14:01:23

bobbym
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Re: Really Difficult Differentiation! Help please!

That is correct! You have one more part to do.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#36 2012-11-28 14:03:42

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

bobbym wrote:

That is correct! You have one more part to do.

YAY! Thank you!

SO, in whole must become, nWYP^(n-1)Pi(-n-1)? (For the bit you asked about before? big_smile)

#37 2012-11-28 14:15:06

bobbym
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Re: Really Difficult Differentiation! Help please!

nWYP^(n-1)Pi(-n-1)?

You left out an exponentiation sign in there.

It is Pi^(-n-1).


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#38 2012-11-28 14:18:24

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

Ah yes thank you bobby, sleep eyes.

Now this term is complete? But when you posted a solution, you had (nWY((Pi/P)^(-n-1)))/P^2 ? How did you get from the differentiated thing to this for this specific term?

#39 2012-11-28 14:21:33

bobbym
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Re: Really Difficult Differentiation! Help please!

There is one more term to be differentiated. When we simplify it all up we will see.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#40 2012-11-29 05:17:29

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

Ok great! Now the last term, want to differentiate (YPi((Pi/P))^(-n))/P. So for this I get (-nYPi(Pi/P)^(-n-1))/P, but I know this is wrong because there are two Pi's and I am only doing one of them, how does this work??

#41 2012-11-29 06:45:06

bobbym
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Re: Really Difficult Differentiation! Help please!

Hi;

We are not done yet, not by a long shot. Which term are we working on?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#42 2012-11-29 07:07:45

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

The last term!

I think when we differentiate it we get (-nYPi((Pi/P)^(-n-1)))/P?

#43 2012-11-29 07:10:34

bobbym
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Re: Really Difficult Differentiation! Help please!

The third term has a P in the denominator. I left it out because we concentrated on the numerator. So we are not done with the third term.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#44 2012-11-29 07:26:47

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

bobbym wrote:

The third term has a P in the denominator. I left it out because we concentrated on the numerator. So we are not done with the third term.

I see, apologies for not making this clear: P and Pi are completely different things.... P could be Y or X for example! It just happens to represent something beginning with P! tongue But Pi is what we want to differentiate with respect to! tongue

#45 2012-11-29 07:39:05

bobbym
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Re: Really Difficult Differentiation! Help please!



We differentiated that when the real problem is this:


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#46 2012-11-29 07:42:25

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

OH, so hwo do we do it?

oh my god why is this so difficult for such a little step, can we please go through this.

#47 2012-11-29 07:47:03

bobbym
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Re: Really Difficult Differentiation! Help please!

Since the P is a constant just take the answer you got and put it over P.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#48 2012-11-29 07:55:15

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

bobbym wrote:

Since the P is a constant just take the answer you got and put it over P.

Ok now I am just getting confused, so that answer I had was correct?

Ok let's just leave this I don't think I can solve this problem anymore. big_smile Thank you though.

#49 2012-11-29 08:04:38

bobbym
Administrator

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Re: Really Difficult Differentiation! Help please!

Hi;

Okay, but we are almost done with the whole problem and are done with the third term.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#50 2012-12-21 02:49:16

BarandaMan
Guest

Re: Really Difficult Differentiation! Help please!

Is there anyone here who can actually help me by explaining this methodically and quickly?

I have exams approaching in January and tried to solve this problem weeks ago. I cannot do it. I do not have the time to spend another 2 weeks trying to be directed to a correct answer. I have memorised the solution so that will be fine (solution is posted), but I do not understand how to differentiate it. Please help me.

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