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#102 Re: Help Me ! » making 100 using four 7 » 2008-05-01 19:06:33

If I understand the question correctly, Its not possible
7*7*7*7 (* is whatever operation you place, + - x /) , the result will always be a mutiple of 7

#103 Re: This is Cool » Inequality matrix algebra? » 2008-05-01 07:06:22

nope, but I guess it would be under the same principle as solving equalities?

#104 Re: This is Cool » 0.9999....(recurring) = 1? » 2008-05-01 03:29:55

moxiuming, please fully understand the concept of infinity......

0.999999.... is represented as, you can even consider it to be a expression which holds the value 1
 

#106 Re: Help Me ! » function » 2008-04-30 09:13:37

I think I could fix the f(h)/h thing

#107 Re: Help Me ! » function » 2008-04-30 08:59:25

Ricky, is my proof under the same principle as your? it looks similar but I dont know if its legal, it goes like this

#108 Re: Help Me ! » function » 2008-04-30 04:07:02

JaneFairfax wrote:

says that f is a homomorphism from the additive group of reals to the multiplicative group of positive reals.

says that f is differentiable and hence continuous.

The only continuous homomorphisms from

to
are of the form
where k is a real constant.

Ah so you can assume its e^kx ? no need to prove that?

#109 Help Me ! » function » 2008-04-30 03:43:23

Dragonshade
Replies: 8


need help with this, thx

I know its easy if you assume f(x) to be n^x, since f(a+b)=f(a)f(b), then find n to be e, but is that enough? I mean it doesnt seem general

I could only get this far

#110 Re: Help Me ! » Folding book » 2008-04-29 08:20:37

Oh, I overlooked something, I could find a formula for  sequence z_i , ok, problem solved, tons of calculation indeed

#111 Re: Help Me ! » Folding book » 2008-04-29 08:07:31

John E. Franklin wrote:

I don't get everything you wrote, but I noticed that the 1st
fold is based off of 2 opposite corners, but the folds after
that probably are cutting the remaining angles in half.
So when I folded it, A1 folded 1st, then A3, then the A2.
Sort of like on a ruler, 1/2's the quarters, the eighths,
the sixteens, etc...

for example, The right triangle C_1 A_2 B is what I got when I folded the second page, making the DB of the second page lie on the A_1B,     then I continue to fold the third page,  I will get another right triangle C_2 A_3 B,  the DB of the third page lies on A_2B..... I could fold infite right triangle in this way, I want to get the sum of these triangles

my apology if I am not clear enough

#112 Help Me ! » Folding book » 2008-04-29 06:19:54

Dragonshade
Replies: 3

I was bored and started folding my book idly

then I started to think what's the sum of the triagles if I fold it like this

Then I started to find the sum


How do I finish it
The sum should be covergent

#113 Re: Help Me ! » Limits: 1^infinity vs. (1-infinitesimal)^infinity » 2008-04-29 04:33:47

but the problem doesnt exist in this case, since cosx cant take 1, 1-cox cant be 0

#114 Re: Help Me ! » find solution » 2008-04-29 04:10:02

click on the calculation other people wrote, you will be able to see the code

#115 Re: Help Me ! » find solution » 2008-04-29 03:20:59

you could click on the LaTeX other people wrote to get the code

#116 Re: Help Me ! » Find the LCM of the following expression:- » 2008-04-29 03:16:26


oops didnt know its to get the LCM lol , fixed

#117 Re: This is Cool » 3D weirdness » 2008-04-28 18:00:06

mathsyperson wrote:

Well yes technically, but the sphere is so huge (and so has curvature so tiny) that the ceiling could reasonably be approximated as a plane.

I wouldn't think that you'd get such a massive discrepancy from the expected 360 degree sum just because the ceiling might be very very very slightly curved.

Hmm,you got a point... isn't that some kind of visual fallacy, then?

#118 Re: Help Me ! » Mechanics » 2008-04-28 08:53:44

I dont think the resistant is to the same direction as the gravity. thereforce they must be of different sign regardless of the observer

#119 Re: This is Cool » 3D weirdness » 2008-04-28 03:51:44

ceiling is not a plane, its a fragment on a sphere, since it's parellel to the ground.

#120 Re: Help Me ! » continuous » 2008-04-28 03:46:00

oh yea, my bad,sorry left limit = right limit...

#121 Re: Help Me ! » continuous » 2008-04-27 19:28:04

its not continuous, x cant take the value 4

#122 Re: This is Cool » 3D weirdness » 2008-04-27 16:50:05

its true if you consider it to be a relativistic space. XD.

#123 Re: Help Me ! » Probability??? » 2008-04-27 08:41:15

P(A)= 1/4?

P(B)= 25/34 ?

P(C)= 1/13?

havent done probability for a long time lol

#124 Re: Help Me ! » Contradiction? » 2008-04-25 12:36:49

Ah, thats clears up a lots. Thanks

#125 Help Me ! » Contradiction? » 2008-04-25 04:31:01

Dragonshade
Replies: 2

I argued with my father about the 0.9999...  question. It's , of course I believe it's equal to 1

 
I said 0.0000(infinty)1 is zero.
He said: consider this function 1/x (x>0). 1/x is not connect with x=0, you couldn't find the integration between [-1,1] directly, have to do it by parts, because its not continous, therefore it's not 0.
I said, the number isnt even a point on this function.  Infinity is not number, you can't substitute in to the function and get that value.
He said, well, what's the least distant between the points on this function and x=0 , it's zero. It's not continuous and now it's continuous .

I think his thinking is obviously flawed, but I couldnt spell it out lol,help

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