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## #1 2014-01-15 10:53:11

ninjaman
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### 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:)

## #2 2014-01-15 14:20:38

bobbym

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### 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.
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.

## #3 2014-01-16 04:48:06

ninjaman
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### 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

## #4 2014-01-16 04:58:11

bobbym

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### 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.
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.