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#42601 Re: This is Cool » 0x∞=-1 ??? » 2005-08-16 19:26:52

Too complex for the human brain to comprehend.....
wcy showed us 0 x ∞ = -1
and there seems to be no loophole in the proof.
I was almost convinced that 0 x ∞ = 0 x 1/0 = 1, now I'd have to tell my mind it is ±1.
When we take the value -1,
0 x ∞ = -1
Taking square root on both sides,
√ (0 x ∞) = √-1
0 x √ ∞ = i
Therefore, √ ∞ = -i/0 !
wcy, your theory appears to be right!

#42602 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-16 16:27:32

Correct, Mathsy!

Problem # n+10

Mathsyperson, Kylekatarn and wcy are a team for solving problems. The possibility of one solving a problem is 45%, the other is 50% and the third is 55%. What is the probability that a problem would be solved?

#42603 Re: Help Me ! » Need help » 2005-08-15 20:39:56

x³ + 2x² - 9x = 18

x³ + 2x² - 9x - 18 = 0
Putting x=3, we find that it is one of the solutions.
Therefore,
(x-3)(x² + 5x + 6) = 0
x² + 5x + 6 = (x+3)(x+2)
Therfore,
(x-3)(x+3)(x+2) = 0
which gives the following values of x :- 3, -3, -2

PS:_ A cubic equation, that is an equation of degree three, can be solved only by trial and error, as far as I know.

#42604 Re: Help Me ! » total square footage of a quonset hut » 2005-08-15 16:37:12

A quonset hut would be half of a right solid cylinder. Length is given as 205  feet. Width is given as 80 feet, and height 24 feet. But if the width is 80 feet, the height would have to be 25.46479 feet. That is obtained by dividing 80 by pi.
The volume would be pi*r²*h/2 = (3.141592 x 648.4556 x 205)/2
= 208,811.285 cubic feet

#42605 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-15 16:10:51

mathsyperson wrote:

So the next number would be 6³+6²+6=258

Mathsy, thats very good!

Problem #n+9

From a well shuffled pack of 52 cards, four cards are drawn one after the other. What's the probability that the four of them would belong to different suits?

#42606 Re: Help Me ! » percent difference between 2 zero values » 2005-08-14 18:04:53

If the value of the current month is B and the previous month A,
[(B-A)/A]*100 is the right way of calculating the percentage increase, which you have done. Problem arises when the difference is 0 and both the values are 0. I don't think there is any mathematical solution, but if you could program in such a way that
the formula is applied only when the difference ≠ 0
and when the difference is zero, the percentage change is zero,
your problem could be solved!

#42607 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-14 15:28:53

You are correct, NIH !

Problem # n+8

Find the next term of the series
3, 14, 39, 84, 155, _____

#42608 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-12 23:53:01

Problem # n+8

Can you find two numbers composed of only ones which give the same result by addition and multiplication?

#42609 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-12 23:44:28

d/dx (logx) = 1/x and ∫(1/x)dx = logx

#42610 Re: Guestbook » Maths » 2005-08-12 20:07:31

Welcome to the forum, Tahlia!
Keep visiting, new pages are being put on the website! You'd love them too!

#42612 Re: Dark Discussions at Cafe Infinity » Ah Yes, Infinity » 2005-08-12 17:11:20

Yes, I used logarithm to the base 10 for convenience.
The idea is to show that
Infinity + 1 = Infinity
Infinity + Infinity = Infinity
Infinity x Infinity = Infinity
Infinity ^ Infinity = Infinity
Infinity ^ Infinity ^ Infinity ^ Infinity ........Infinite times = Infinity
This is true because because we can never say for what value of n
log(n)infinity would be undefined.
And this is only the fourth stage of iteration (also referred to as 'tetration').
No wonder, Infinity is beyond comprehension for the human mind!

#42613 Re: Dark Discussions at Cafe Infinity » Ah Yes, Infinity » 2005-08-11 23:54:58

Definition:-
log (x) is denoted as log(1)x
log (log x) is denoted as log(2) x
log[log(logx)] is denoted as log(3)x
and so on.
We know that log of zero or a negative number is not defined.
My question is, for what value of n would log(n) ∞ i.e. log(n)infinity, be not defined?
(eg. log(6)Googolplex is not defined.)

Warning : We are moving from infinite to transfinite cool

#42614 Re: This is Cool » 0.9999....(recurring) = 1? » 2005-08-11 22:42:23

wcy wrote:

a = 1
b=0.0000000000000000...1
a-b=0.99999999....
a²-b²=1²-0.000000....1=0.99999999...
(a+b)(a-b)=a²-b²
a+b = (a²-b²)/(a-b)=0.9999.../0.9999...=1
a=1
therefore b=0 !!!!
therefore a-b=0.999999...=1-0=1  !!!!!

If we are talking of infinite number of zeros after the decimal, before the 1, in b,
the proof is correct!
Because, a²-b² would be equal to a-b.
This is because we have defined 0.0000000000.......1 as 1 ater an infinite number of zeros after the decimal followed by 1,
as kylekatarn denotes 0.(0)1.


However, if the number of zeros is finite, (Don't worry, it is not)
a²-b² would contain more 9s than a-b.

#42615 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-11 22:28:30

Mathsy, you are right.
But, this can be done with Calculus.
Let x^x = y
x logx = log y
Differentiating both side,
xLogx(1) + x(1/x) = d(logy)
logx + 1 = d(logy)
When this is equal to zero,
Logx + 1 = 0
Log x = -1
      x = e^-1 = 1/e
This is because logy is minimum when y is minmum smile

#42616 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-11 22:23:33

Oops, I made a mistake.

If, as I had said earlier, x∈ Real numbers,
my question would have no answer as
(-1 x 10^n) -1 would give a negative odd number for a
large value of n (n ∈ Natural Numbers).  And this number raised to itself would give a negative number which would be much lesser than zero!
Therefore, the smallest value would be -∞

I forgot while posting that one that a^-n = 1/a^n
Therefore, the minmum value of x^x is not -∞
I am sorry I wasn't concentrating 100% smile

#42617 Re: Help Me ! » I need your help » 2005-08-11 22:20:56

You are right, MathsisFun. I am working on this. I shall give you the details next week.

#42618 Re: Help Me ! » I need your help » 2005-08-11 21:17:49

0^0^0 is not defined.
But for 1, as you pointed out,  2^Mx > x^x^x.
For this problem, let us take value of x ≥ 2, x ∈ N

#42619 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-11 21:12:32

Am I allowed to slightly modify my question?
If yes, the question should read
'For what value of x is x^x the minimum, x>0?'
If, as I had said earlier, x∈ Real numbers,
my question would have no answer as
(-1 x 10^n) -1 would give a negative odd number for a
large value of n (n ∈ Natural Numbers).  And this number raised to itself would give a negative number which would be much lesser than zero!
Therefore, the smallest value would be -∞ smile

#42620 Re: This is Cool » 0.9999....(recurring) = 1? » 2005-08-11 16:38:43

kylekatarn wrote:

I don't know if the way I represent the infinitesimal quantity ( 0.(0)1 ) is mathematically correct. But I found it very usefull while researching on this.

0.(0)1 is 1/(10^ ∞)
When I had to deal with numbers like 9.9999999999999999999....8,
I put a horizontal arrow pointing towards the right above the 9 after the decimal.Then I put the number 8. This meant that 9 keeps on recurring but the last digit is 8. But your method seems better, more convenient. Whether it would be accepted by Mathematicians worldover is another thing!

But the point I wanted to make is 0.999999999999...................... is a devilish number and would never be found in any mathematical problem or solution. It cannot be represented in a graph, It cannot be said to be irrational, yet it cannot be expressed as a rational number. It is not a transcendental number. As a rule, it should be possible to represent all decimals as a rational number. But this number defies the rule, although it is a recurring decimal. Sin 89.99999999999999999999999999999........ degrees can be said to be equal to this number. 

I give up..........

#42621 Re: Help Me ! » I need your help » 2005-08-11 16:10:13

If Mx is the Least Common Multiple of all numbers from 1 to x,
can it be proved that
x^x < 2^Mx  < x^x^x ?
The second part is very simple. 2^Mx is certainly less than x^x^x because both the base and the exponent of 2^Mx are lesser than x^x^x.

#42622 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-08-11 16:07:26

Problem # n+7

If x ∈ Real Numbers, What is the minimum value of x^x?

#42623 Re: Maths Is Fun - Suggestions and Comments » Online poll for website » 2005-08-10 16:46:48

A poll like...
Which part of Mathematics I hate the most?
(a) Calculus
(b) Trignometry
(c) Probability
(d) Algebra
(e) Vectors and Mechanics
(f) Number Theory
.........etc. big_smile

#42624 Re: Jokes » Tellytubbies are evil! » 2005-08-10 16:41:34

Reminded me of one of Murphy's Love Laws:-

Brains x Beauty x Availability = Constant tongue

#42625 Re: Dark Discussions at Cafe Infinity » Wink Murder 2 » 2005-08-10 16:08:04

A stranger offered me a bottle of coke. Coke has always been my favorite. How could I resist? Without any suspicion, I drank the entire 300 ml. Later, I started feeling dizzy and I realized I was poisoned. But it was too late. My legs were too weak to carry me and I fell dead.

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