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#1 Re: Help Me ! » Stuck on a chain rule prob » 2011-08-08 18:30:35

Yes I am good. Supposed to be starting work this week, the place
called last week to say they were moving all their kit over to a new
office and then getting me in after that. All excited smile

Other than that just been going over things I have forgotten and trying
to get MATLAB to do fractals. This has of course meant brushing up on
complex numbers and infinite series.

I sort of understand how it works, but not enough to get it to work inside

Maybe I should start a new post on that?

#2 Re: Help Me ! » Stuck on a chain rule prob » 2011-08-07 21:55:46

Hi Bobby

Thanks for that.

Yes I understand now. Just worked the rest of the remaining problems on the exercise
and got them all.

More reading needed though.

#3 Re: Help Me ! » Stuck on a chain rule prob » 2011-08-07 17:40:58

Hi All

I think I get it now. So in this one the chain rule is only supposed to be used on the
first e term and then the

term is done separately on its own at
the end.

Something like this.

This book never even mentioned anything of the sort. Though I suppose it is meant
for tutored lessons.

#4 Re: Help Me ! » Stuck on a chain rule prob » 2011-08-07 05:39:09

Hi huys

I'm just following this book I have and the questions are supposed to get you
used to using and understanding the idea. Up until this one they pretty much
the same. Some log, some trig some simple composite functions.

in the book it says the chain rule is

this works fine for

The problem is I don't know how to handle to 6x^2 term, in terms a composite function.

if i make


i then make

it is on

where I get stuck.

#5 Help Me ! » Stuck on a chain rule prob » 2011-08-07 02:21:33

Replies: 13

Hi All

I have been doing o.k with this stuff so far, but have hit a block with one of them.

here it is.

if I do


i can't get the required


i suppose what I am asking is how do I split this up into two functions.



#6 Re: Help Me ! » Naturual Logarithms » 2011-06-27 22:56:27

I know, I was bad and didn't do any maths for months. Never been good at time management
and seem to throw myself completely at things, in this case trying to get a a job.

I was always thinking about maths and felt bad that I wasn't doing any, so about a month ago I
picked up the books again and decided to just do 2 hrs a day. So now I can do both look for a job
and do maths.

Winning Combination, and I am much happier now smile

#7 Re: Help Me ! » Naturual Logarithms » 2011-06-26 22:47:02

Hello all.

It has been so long since i was last on here. I fell out with maths as I was stuck on the original problem of this post. However since picking it all up after a break I have now got it smile 

Just shows that a break works wonders.

And thank you Bobby, the raising both sides to e^x works a treat.

Got to take the little one to school now.

#8 Re: Dark Discussions at Cafe Infinity » Slot Cars » 2011-01-29 09:41:53

Cool, good to hear you are o.k

Yes some scaling sounds like it would be just the job.

Things are still the same here, got an interview on the 4th. Not that bothered about it to be honest. IT Dogsbody, Bahhh!! Rubbish! . So i've started to work on building a Chroma Key program in MATLAB. Far more interesting. smile


#9 Re: Dark Discussions at Cafe Infinity » Slot Cars » 2011-01-29 05:52:55

Oops was thinking about something else when i worked that out

64m and 209.973ft smile

#10 Re: Dark Discussions at Cafe Infinity » Slot Cars » 2011-01-29 05:50:32

Hi Bobby and Bob

Yes I thought it was very wrong. Just wanted to discuss the matter and clarify it with the dudes. smile

Also it crashed and flew about 2m into the air. So by their reckoning that's 192m or 629.921ft


Hows things anyway? Hope all is well with you both.

#11 Dark Discussions at Cafe Infinity » Slot Cars » 2011-01-26 23:53:27

Replies: 7

Hi Guys

I was just watching a program where there was some slot car racing. They said the cars were 1:32 scale. And then they raced down the track and measured the speed. When the speed was recorded they multiplied it by 32 and came out with values around 6-900 MPH.

This seems incorrect to me, what do you think?


#12 Re: Dark Discussions at Cafe Infinity » Flat Earth Society » 2011-01-07 21:07:30

They are on giant treadmills with dynamos attached. This is how the electricity is produced in the new order. No need for solar cells.

#13 Guestbook » Happy New Year » 2010-12-28 22:39:05

Replies: 3

Happy Holidays and a Happy New Year to All

Dave, Kate and Emma

#14 Re: Dark Discussions at Cafe Infinity » Flat Earth Society » 2010-11-03 21:56:04

I went for an interview yesterday. I had to travel 40miles into West London and when I got there (it was supposed to be at a Media Exhibition) the woman at the gate flatly refused to let me in. (Punn Intended). So I went all that way, missed the last bus to my village, walked home in the rain. I think this person definitely would believe that the earth is flat and suspended on four elephants. Or even on the shell of a giant turtle.


#15 Dark Discussions at Cafe Infinity » Flat Earth Society » 2010-10-27 20:38:29

Replies: 25

Hi All

Has anyone heard of this group?
Visited their website and read the physics on there?

Personally I don't see how they can come to the conclusions that they do when it is so well known that when you go very high you can see the curvature of the earth. Also when you go higher than that the earth is quite clearly a sphere.

And all the information they call facts are taken from some 19th century pastor.


#16 Re: Help Me ! » log question » 2010-10-27 20:34:33

Hi Guys

This is cool, always wondered how you would operate with Power Towers since Bobby first mentioned them to me. A while back now I know smile

#17 Re: Help Me ! » Simple Mechanics Problem » 2010-10-02 21:55:35

Hi guys

Sorry for the delay in reply again. I did get it on wednesday, seems so silly now.

I'm liking Mechanics, it gives you real examples and uses for all the Pure stuff I have and am learning.

Here was my solution

then :


then :

This is the answer given in the book, so I assume it is correct. Though it would be nice to have some
confirmation from the guys.

Thanks for all the help


#18 Re: Help Me ! » Naturual Logarithms » 2010-10-01 20:29:39

Wow.. 3 pages! What have I started! smile

Hows things guys? Hope all is well

#19 Help Me ! » Simple Mechanics Problem » 2010-09-20 20:11:52

Replies: 3

Forgive me father, it has been 2 weeks since my last confession. I've been prepping for an interview. (no excuse i know wink)

I have started mechanics and so far so good, until I came across this one. It's had me stumped for a week now, probably simple I just can't see it.


The V-T graph shows the motion of a car and a bike as they travel along a straight road.
When t=0, the car and the bike pass a traffic light on the road.
At the traffic light the bike is travelling at 5ms-1 and the car is doing 3ms-1 and accelerating.

a) Explain how the graph indicates that the acceleration of the car is constant.
b) Find the acceleration of the car.
c) When t=T the car has travelled twice the distance of the bike. Find the value of T.

I can do a) and b) no problem, it's c that has me stumped and the more things I try the more confused I am getting about it.


Thanks guys.

#20 Re: Help Me ! » Scientific Notation » 2010-09-10 00:22:27

Hi Bob
Sorry for the delay, been a while since my last post.

Love it :---- houseboat smile

#21 Re: Help Me ! » Curve Fitting » 2010-08-27 00:42:31

Hi Bobby

Yes I see. The least squares fit is more accurate over a large number of points, than it seems to be with a small number.

You always see these diagrams in books with 5 or 6 points and fitting doesn't look that good.

#22 Re: Help Me ! » Curve Fitting » 2010-08-27 00:02:58


Yes, just been looking at Linear Interpolation on Wikipedia. I can see how that it complicated and would take some time.

#23 Re: Help Me ! » Curve Fitting » 2010-08-26 22:53:50

Hi Bobby

Thanks for this, I will have a go with that one.

Is there some process that you used to get the result, that works universally or is it dependent on the data?

#24 Re: Help Me ! » Curve Fitting » 2010-08-26 22:40:32

not sure, I am just trying to put what I have learned to some practical use.

Say I go out everyday and measure the growth of a plant, and wanted to find the rate at which it is growing on a particular day.

I suppose what I am asking it how do you create a polynomial that fits the data.

#25 Re: Help Me ! » Curve Fitting » 2010-08-26 22:30:24

Would you have to do something like Fourier Analysis to get a smooth curve?

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