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#1 2014-01-14 11:53:11

ninjaman
Member
Registered: 2013-10-15
Posts: 41

differentiation

hello
I have a question im stuck with

y = (7x-4) 3/2         (3/2 is supposed to be 3 over 2, I don't know how to do that on here)

I got this,

u = 7x-4

du/dx = 7

y = u 3/2

dy/du = 3/2u -3/2  (the -3/2 is power, supposed to be above right of u)

du/dx * dy/du = 3/2u-3/2 * 7 = 21/2 u -3/2

since u = 7x-4,      21/2 (7x-4) -3/2

im thinking most of it is correct except for the -3/2, the fraction part has me concerned.

thanks

simon:)

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#2 2014-01-14 15:20:38

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,460

Re: differentiation

Hi;

ninjaman wrote:

dy/du = 3/2u -3/2  (the -3/2 is power, supposed to be above right of u)

You made a mistake in the above step. You did not apply the power rule correctly. Here are the steps for the whole problem.

You can use latex for all your math posting. I use this when I am not doing it by hand,

http://latex.codecogs.com/editor.php


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#3 2014-01-15 05:48:06

ninjaman
Member
Registered: 2013-10-15
Posts: 41

Re: differentiation

thanks a lot, I looked at the bit where you put in a radical(I think that's what its called, the sqrt sign) that threw me.
thanks also for the latex thing, that will help a lot when writing out maths stuff!

all the best
simon

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#4 2014-01-15 05:58:11

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,460

Re: differentiation

Hi;

It makes perfect latex so everything looks nice and neat.


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

Online

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