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#51 Re: Help Me ! » How to solve this eqation? » 2006-07-26 07:57:57

1) First, solve for K using your second equation:



2) Now, note that T=70-c and our K above, use your third equation:

Move over 70, and use that (110-T)/c = (c+40)/c (which you can get from 110=T+c+40 in equation 2)

But e^ln(a)=a, so

Which gives c=-320.


3) So T=70-c=70+320=390.

#52 Re: This is Cool » Pi to a Million Decimal Places! » 2006-07-24 09:47:04

The site works here, and I think I've seen it before too, heh.

Have you seen the record list, Devanté? I know there's a list with people who holds some kind of record in memorizing pi digits somewhere online. I don't know if it was official, and I don't have the site url, but try searching google and you might find it. It was pretty insane, but I'm pretty sure it wasn't close to a million though! wink

#53 Re: Help Me ! » 2+2 = 3.99 recurring?? » 2006-07-24 04:45:01

Yes, but these are the same number smile (yes, I've realized that now, sorry!)
They're just presented differently, 4 or 7-3 or 3,999... but if a number like 3 would equal another number 4 you'd have big problems!

#54 Re: Help Me ! » oooohhh...and.. » 2006-07-24 04:36:17

I've had a calculator that gave me the wrong answer once (for real! and I threw it away too!), so I don't always trust them tongue
Learn the trick John described, sooner or later you'll be using it for polynomial division anyway wink

#55 Re: This is Cool » pi and other numbers with infinite numbers of decimals » 2006-07-21 21:04:37

luca-deltodesco wrote:

infinate amount of numbers doesnt mean infinate amount of combinations, take for example

0.1111111111111111111....111112

i.e. infinate 1's then a 2, infinate numbers, no pattern, but you can only get a combination involving 1's, or 1's with a 2 on the end

But luca, that doesn't make any sense. If there was an infinite amount of 1's, then they wouldn't stop and suddenly end with a 2, because then the 1's must be finite. neutral

#56 Re: Help Me ! » 2+2 = 3.99 recurring?? » 2006-07-21 07:29:17

If that proof is true, then 3,999... is in Q.

If 1,999... = 2, then we could multiply both by 10000...
thus, 1999... = 2000... right?

Actually, I don't think I'll continue from here, I'm really confused now... tongue

#57 Re: Help Me ! » 2+2 = 3.99 recurring?? » 2006-07-21 06:36:03

ben,

1/3+1/3+1/3=1.

But note that 0,333... is not 1/3, it's an approximation.
It's just slightly less than 1/3. It approaches 1/3 like a limit, but never becomes it. 4 is in Q, 3,999... isn't.

Keep in mind that an infinitely large amount of zero's adds up to zero, while infinitely small is larger than 0. The difference is infinitely small, thus not equal to zero, so they're strictly not the same.

#58 Re: Help Me ! » eletronic problem but mainly aleg and simultanious » 2006-07-21 04:09:46

Yeah, true that, and the prefixes are important. Here's how I'd do it:

Split up the same way Ricky did and introduce a variable A for simplicity

Now we have:

From here, you can simplify the root (check it yourself):

#60 Re: Help Me ! » 2+2 = 3.99 recurring?? » 2006-07-20 11:26:19

Is (...) supposed to mean limit? Now that's new.

Besides, I think this would be a valid argument against it:


Edit: 3,999... is not irrational by definition so it has to be rational, so I take the above statement back. tongue

#61 Re: Help Me ! » why mathematical induction works? » 2006-07-20 03:52:13

Ricky: ok, perhaps I should've worded it correctly, would an equivalent statement make more sense?

Since; All odds are prime numbers <--/--> 3,5 and 7 are prime

#62 Re: Help Me ! » why mathematical induction works? » 2006-07-19 22:13:46

The point is that if you prove that if it is true for n=k, it is also true for n=k+1. If we end up with a statement which is true based on that assumption, it means that the assumption we made is true. If, however, we'd end up with a false statement as a result of that, our original assumption would be wrong.

You can look at it this way:

1) If x is true --> y is also true
2) If x is true --> y is false

1) If our assumption x is true, it leads to a statement y which is true. So our assumption must be correct.
2) If our assumption x is true, it leads to a statement y which is false. So our assumption cannot be correct.

Apply this to your problem. If what you are saying is true, two of those formulas should lead to a false statement, meaning that the assumption that it is a formula for the sum of natural numbers is false.

#64 Re: Puzzles and Games » Sudoku Puzzle Variants » 2006-07-17 22:17:12

solved the first 4 :] actually, the first two were just naked singles all through, no fun hmm

#65 Re: Puzzles and Games » Sudoku Puzzle Variants » 2006-07-17 21:31:16

I'll have a go at the top four ones. The other variants appears to be to messy, I prefer the original way smile

#66 Re: Help Me ! » Please help me to solve the following problems » 2006-07-16 10:10:42

Nice John, 12^(3 1/3) is a much better answer :]

#67 Re: Euler Avenue » An abstract introduction to Groups and Fields. » 2006-07-16 09:44:44

This is great reading, nice work Ricky and ben! :]

#68 Re: Help Me ! » Please help me to solve the following problems » 2006-07-16 02:34:03

Hmm, ok I'll take it as my first suggestion then and lets see what I get.

We have that


The second equation says that L has increased 1% (1,01) and gamma is the change in K, which we should solve. Set them equal to get rid of Q:

Since

we can divide with K^0,8 and L^0,4 to get

So,

Which is approximately 0,99504... in other words a decrease by 0,5%.

#69 Re: Help Me ! » I am so sick of staring at this puzzle... please help.. » 2006-07-16 01:57:55

Don't write equations like that tongue It's rather (1+6)+(3+1)=11.
And yes, it seems like it's a two-digit number, and not 1-digit.

#70 Re: Help Me ! » Please help me to solve the following problems » 2006-07-14 22:49:04

1. x=25/10=5/2. [divide by ten on both sides]

2. 10e^x=160 -> e^x=16 -> x=ln(16) [subtract 40, divide ten, logaritm both sides and ln(e)=1]

3. ln(x^0,3)=ln(12) -> ln(x)=ln(12)/0,3 -> x=e^(ln(12)/0,3)  [logaritm both, down with 0,3; solve for x]

4. ln(x)*ln(e)=ln(8) so ln(x)=ln(8), thus x=8. [logaritm on both sides, ln(e)=1]


5. Do you mean Q=K^(0,8)*L^(0,4) or Q=K^(0,8(L)^(0,4)) or something else?

#71 Re: Help Me ! » What does this symbol mean (^)? » 2006-07-14 22:35:58

3^(2x) means 3 raised to the power of 2x.

#72 Re: Introductions » Hi all =D » 2006-07-11 22:18:23

Welcome Ross!

Your swedish is fine, lol. I hope you enjoy your stay here :]

#73 Re: Help Me ! » Help is appreciated!! » 2006-07-09 12:42:44

Set up an equation, the average of the last three games should be 152 for him to maintain his total average of 152:

You've started a whole lot of topics lately, have you actually tried solving them yourself?

#74 Re: Dark Discussions at Cafe Infinity » World Cup 2006 » 2006-06-20 00:48:18

Being swede, I'm really looking forward to the game against england today smile

#75 Re: Help Me ! » Differential Equations » 2006-06-20 00:32:25

Ok, well then you could find the particular solution by using the fact that

So you'd get the equation

Where the particular solution can be solved with the approach

And you could always rewrite the homogenous solution with exponentials and sin/cos instead of expoentials with i if that makes it easier.

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