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#76 Help Me ! » Scientific Notation » 2010-05-30 18:27:49

DaveRobinsonUK
Replies: 17

Hi Guys

I have something that has been bothering me for a few months now and the other day it popped up on a problem I was working on. The actual maths in terms of arithmetic operations was straight forward enough, but the solution was to be given in the correct units and I wasn't sure what they should be.

The example was as follows

where
,
and

The thing I have been wondering about is why some units are

and others
. Does it mean the order of the derivative taken to calculate it?

Thanks in advance.

David

#77 Re: Help Me ! » Simultaneous Logarithms » 2010-05-18 20:35:18

DaveRobinsonUK

Hi Bobby

Got it..

In the book for the course there is no mention of disregarding the logs and just working the equations.
It makes a huge emphasis on the use of the indices laws and lots of questions using that and then
throws curve balls like this one, still it is good that it does.

I suppose it stops you from becoming complacent and thinking you can breeze through.

Thank you Bobby.

I'll have a go at the Simultaneous one now.

#78 Coder's Corner » Complex Number Representation » 2010-05-18 20:13:59

DaveRobinsonUK
Replies: 1

Hi All

I am having a go at a small program to draw a fractal, though I am not sure on how to represent the
imaginary part of the complex number.

Most examples I have seen use a pair of doubles, though I can't see how they are representing i.

The one I am looking at now is coded in C++ as

// Function that multiplies two complex numbers
   // the result is a modified object of the class (this)

   void Multiply(Complex_Number comp_num)
   {
       double temp_a;
      double temp_b;
      temp_a = this->a * comp_num.a;
      temp_a += (this->b * comp_num.b)*(-1);

      temp_b = this->a * comp_num.b;
      temp_b += this->b * comp_num.a;

      this->a = temp_a;
      this->b = temp_b;
   }


then multiplying the b value by -1. I thought only

was equal to -1.

It's probably just me being thick, though if someone could explain how this is working
that would be cool. big_smile

Thanks

David

#79 Re: Help Me ! » Simultaneous Logarithms » 2010-05-18 19:57:37

DaveRobinsonUK

Morning Bobby

i've worked through the solution you gave


->

->


is it reasonable to remove the fraction by multiplication


->

do I have to expand the LHS and RHS and subtract

from the RHS.

I really want to work this out, but every now and then I get stuck like this.
Sorry neutral

#80 Re: Help Me ! » Simultaneous Logarithms » 2010-05-18 07:57:55

DaveRobinsonUK

Hi Bobby

I've got to get Emma ready for bed, she's already late. Gone 8PM here, (late enough for a 2 year old girl)
so I'll have to leave it until the morning.

Hard work, trying to learn math and bringing up a toddler smile

Talk soon and night night. smile

David

#81 Re: Help Me ! » Simultaneous Logarithms » 2010-05-18 05:03:23

DaveRobinsonUK

I'm just about to sit down for dinner, I'll have a go in a short while and get back to you on that smile

Thank you.

#82 Re: Help Me ! » Simultaneous Logarithms » 2010-05-18 04:41:40

DaveRobinsonUK

Hi Bobby

The answers in the back of the book ask for numerial solutions for n, apparently they are 2 and 4.

#83 Help Me ! » Simultaneous Logarithms » 2010-05-18 01:58:02

DaveRobinsonUK
Replies: 12

Hi All

In the past week I have been learning logarithms for the first time and so far it has all been good, until
I came across the following 2 equations right at the end. The problem I have with the first is that none
of the others have add/sub operations in the brackets. And the second is a simultaneous solve and I am
not sure how to approach it.

Here are the offending articles..

   Give 2 integer values for n.

and the system is as follows



Give values for both x and y.

On the first, I am not sure where to begin. I have tried a few different things and just seem
to get in a muddle.

on the Second if I expand the top one out to

and then there would be equal coefficients, but I don't know
if the bottom is multiplied together? There is no operation specified, if it is multiply can I still cancel
it out and subtract the remaining parts?


All help as always, very gratefully appreciated.

Thanks
David

#84 Re: This is Cool » proof that 2=2.82 thus that algebra has a huge fault » 2010-05-17 08:32:52

DaveRobinsonUK

Hi Saundo

Are you using a calculator? If so are you pressing the equals sign when you add x+y or entering x then add then y
then the sqrt.

I get 1.4142136, which is the approximation of the sqrt(2) and when I then press = I get 3.4142136

The reason for this is that calculators and programming languages evaluate certain operations before others
usually following the BIDMAS rules. Since SQRT() is a division operation it would be evaluated first on the
associated number, which is 2.

If you have a bracket function, you should get 2. The correct answer should be (+/-2)

#85 Re: Puzzles and Games » Metamorphosis » 2010-05-17 08:07:33

DaveRobinsonUK

PLAY
FLAY
FLAK
FLAT
FLIT
FIRE

ARRRR! I'm going to bed. smile

#86 Re: Maths Is Fun - Suggestions and Comments » College Algebra - Volunteers Wanted » 2010-04-30 20:05:50

DaveRobinsonUK

Will do Maths.

I have been through the long mult and div sections so far. And all is well.

We're off to Corsica tomorrow, so it might be a week or so before I can get some
more done.

#87 Re: Maths Is Fun - Suggestions and Comments » College Algebra - Volunteers Wanted » 2010-04-29 19:05:57

DaveRobinsonUK

Hi Maths

I have had a read through the introduction so far and it's perfect for me, just the sort of thing I need, so I am going to work through it.

Thank You.

"no doubt I'll get stuck somewhere smile"

#88 Re: Help Me ! » How would you work out the odds of you winning the lottery » 2010-04-29 08:34:42

DaveRobinsonUK

Hi Geodude

The numbers I have used are just examples, though the 49 choose 6 is from the UK National Lottery. The rules are that you have 6 numbers to choose. and numbers 1 through 50 to choose from. The balls come out of a machine in two games on the BBC every Saturday and Wednesday. I did the very first game and in the run up made a program to decide my numbers for me, then I sat there planning what I was going to spend the money on. You won't be to amazed to hear that I didn't win.

#89 Re: Help Me ! » How would you work out the odds of you winning the lottery » 2010-04-29 05:39:54

DaveRobinsonUK

Its pretty easy, though it does mean that only one of each number may be picked, and only works one game at a time.

The is a binomial coefficient, it means 49! (49 factorial) divided by 6factorial by 49 - 6 factorial.

So for a smaller example lets say

you have

or

and in general

This is the way in which Camelot calculate the odds for the UK National Lottery, well I assume so as
this method gives the same odds as they give. Around 13million or 13983816 to one.

More chance of jumping off Sears Tower and a gust of wind catching you and neatly placing you back on top,
whilst meanwhile another gust of wind grabs a beer from someone standing outside a bar and simultaneously
places it into your hand.:P

#90 Help Me ! » The best way into multivariate calculus » 2010-04-29 03:56:13

DaveRobinsonUK
Replies: 2

Hi All

Does anybody have any tips for a route into working with multiple variables.

Books
Websites
PDFs
etc

Thanks in advancewave

Dave

#91 Re: Help Me ! » How would you work out the odds of you winning the lottery » 2010-04-29 03:52:14

DaveRobinsonUK

49 choose 6

I think thats right, though it depends on the number of options you have in your lottery.

#92 Re: Dark Discussions at Cafe Infinity » Other Forums, are they rude? » 2010-04-28 19:27:16

DaveRobinsonUK

Hi Bobby

I don't believe there is. The satisfaction to be had when you work something out and the program it in and see it come to life is the sort of thing to make you run about the house shouting and cheering.

smile

#93 Re: Dark Discussions at Cafe Infinity » Other Forums, are they rude? » 2010-04-27 23:12:42

DaveRobinsonUK

Hi MathsIsFun

Yes, I believe AS3 is much better than AS2 with regards to OOP. I used to work as a COBOL programmer, though I was made redundant and decided to make a career direction and worked retrained as a Graphic Designer, which I was recently again made redundant from, which is why I find myself doing nothing but maths and learning C++ and MATLAB.

The way I see it, if I can eventually get a degree in Maths I have a great deal of options with regards to employment, and also something which is limitless with regards to learning.

bobbym wrote:

I love it when someone will follow you around from forum to forum to berate your posts

That's hilarious, I've never heard of that.roflol

#94 Re: Dark Discussions at Cafe Infinity » Other Forums, are they rude? » 2010-04-27 19:46:00

DaveRobinsonUK

I once had to write a flash based web page for job at work, and there was all this AS in it.

Anyway this was AS2 and the site needed something I didn't know how to do, due to it not supported proper OOP so I posted the question on a forum and got huge amounts of stick.

A lot of it was personal too. In the end I snapped and told them to learn a proper language and never went back. Not my finest moment. tongue

This forum is utterly different, I love coming here. Everybody is so kind, understanding and helpful.

#95 Re: Dark Discussions at Cafe Infinity » And the beasts of the field... » 2010-04-27 19:28:27

DaveRobinsonUK

I think I'll stay in the UK..

#96 Re: Help Me ! » Finding the limit of a sequence (BASIC) » 2010-04-27 05:03:23

DaveRobinsonUK

Got it.

Finally big_smile

I seemed to be going wrong in the way I was placing my brackets and incorrectly grouping
the terms.

Thank you so much Bobby.

Time for Emma's Dinner and Bath smile

David

#97 Re: Help Me ! » Finding the limit of a sequence (BASIC) » 2010-04-27 04:32:07

DaveRobinsonUK

Yes I follow up until this point, I seem to go wrong when adding the next fraction.

#98 Re: Help Me ! » Finding the limit of a sequence (BASIC) » 2010-04-27 04:20:23

DaveRobinsonUK

Hi Bobby and ZHero

when I plug in a = 1 and b=1 to the original problem I get

last time I think I went wrong by factoring out an

I did it again and got this.

however, when I plug a=1 and b=2 into this I definately do not get

Thanks
David

ps. should I continue this on another post about algebraic fractions.

I must seem to you like my daughter seems to me, trying to put the square
into the round hole wink

#99 Re: Dark Discussions at Cafe Infinity » Graham's Number » 2010-04-27 01:49:06

DaveRobinsonUK

Hi Bobby

Wow, I thought it would be very complicated. I watched a documentary a while ago on Infinity and Ronald Graham came on discussing how he decided one day to stop being a Circus artist and become a Mathematician and he explained how he came up with them number.

Are the carrats in your 9^(9^(9^9) Knuth notation?

#100 Re: Help Me ! » Finding the limit of a sequence (BASIC) » 2010-04-26 09:57:22

DaveRobinsonUK

Hi Bobby

I think I have it.

Thank you

David

ps
its 11pm here so I'll get off to bed and check this in the morn.
smile

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