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Post: Good maths problem!
09-13-2010, 06:50 AM #1
xOMANx's Avatar
xOMANx
Can’t trickshot me!
(adsbygoogle = window.adsbygoogle || []).push({}); Can anyone work out the answer to the below... I thought it was a pretty good one! Make sure you read it carefully!!!:

What is the four digit number in which the first digit is 1 quater of the last digit, the second digit is 6 times the first digit, and the third digit is the second digit plus three?

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Congrats Juko18!! You got it right!!!
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09-14-2010, 07:42 PM #20
Fionn's Avatar
Fionn
Banned
Originally posted by elfmotat View Post
It's not sin²(x), it's sin(x²). The x is squared, not the sine function so identities don't work.


Oh shit. I thought I did do x squared?
No doubt it has to do with Fresnels so I'll have another go.
09-14-2010, 07:52 PM #21
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elfmotat
Rᵤᵥ - ½gᵤᵥR ∝ Tᵤᵥ
Originally posted by FionnDawg View Post
Oh shit. I thought I did do x squared?
No doubt it has to do with Fresnels so I'll have another go.


We may have a winrar... awaiting results.
09-14-2010, 08:04 PM #22
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Fionn
Banned
Originally posted by elfmotat View Post
We may have a winrar... awaiting results.


Urgh. I have been looking about Fresnals integral on wikipedia.
I think I may have got the first half, I will keep going and post results.
09-15-2010, 07:23 AM #23
xOMANx's Avatar
xOMANx
Can’t trickshot me!
Sorry elfmotat... i don't know how to work that prob. out yet......
09-16-2010, 01:53 AM #24
George's Avatar
George
Originally posted by elfmotat View Post
That... wasn't good at all. I have a better one:

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If anyone solves this I will be highly impressed. (Show work plz).


It has no finite solution.

But I'll have the series solution for you tomorrow.
09-16-2010, 01:58 AM #25
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FourzerotwoFAILS
COD4 God
Originally posted by elfmotat View Post
That... wasn't good at all. I have a better one:

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If anyone solves this I will be highly impressed. (Show work plz).


I'm stuck at this part:

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The following user thanked FourzerotwoFAILS for this useful post:

09-16-2010, 02:04 AM #26
elfmotat's Avatar
elfmotat
Rᵤᵥ - ½gᵤᵥR ∝ Tᵤᵥ
Originally posted by EvilRip View Post
It has no finite solution.

But I'll have the series solution for you tomorrow.


You're right, it has no elementary solution. The series solution can be used to a certain degree of accuracy (just integrate as many terms as you like), but can't be expressed exactly.

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Fionn solved it with a Fresnal integral:

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09-16-2010, 02:13 AM #27
George's Avatar
George
∫sin(x^2) = (x^3/3) - (x^7/7*3!) + (x^11/11*5!) - (x^15/15*7!) +/- ...

cba to LaTeX lol
09-16-2010, 06:54 AM #28
xXviciousbumXx's Avatar
xXviciousbumXx
At least I can fight
God i hated calculus Not Happy or Sad

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