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  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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#42476 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-10-13 20:44:46

Excellent! I used a

method for finding the solution.
Well done,  you have made a great start!

#42477 Re: Help Me ! » Integration by substitution » 2005-10-13 19:02:47

A little further.....
(-1/6) ln( 1-2x^3 )=
ln[1/(1-2x^3)^1/6]
MathsIsFun had done it right, I posted this
.... just to complicate things big_smile

#42478 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-10-13 16:58:27

Problem # k + 29

If each interior angle of a regular polygon is 150 degrees, how many sides does it contain?

#42479 Re: Maths Teaching Resources » Basic Algebra for Form1 students in secondary schl » 2005-10-13 16:29:16

I was first taught the difference between variables and constants.
Thereafter, the lessons were on simple operations of addition, division, multpilication, subtraction, extracting roots, exponentiation etc.
The next step was solving linear equations in one variable, simultaneous equations of two, three variables. A little later I learnt solving quadratic equations and their properties. I forgot to mention, I was also taught plotting graphs and solving equations with graphs.
The Binomial theorem was the last I was taught, and Pascal's triangle too.

#42480 Re: Jokes » Proof :- e equal to one » 2005-10-13 16:12:34

You are right, this was a proof I found in a Mathematics Jokes page.
It is obviously faulty, and you have said where the error lies. I too had figured it out, but left it open for discussion.

#42481 Jokes » Proof :- e equal to one » 2005-10-13 00:06:08

Jai Ganesh
Replies: 4

Proof :- e equal to one
Theorem: e=1
Proof:
2*e = f
2^(2*pi*i) x e^(2*pi*i) = f^(2*pi*i)
We know e^(2*pi*i) = 1

Therefore:
2^(2*pi*i) = f^(2*pi*i)
2=f
Thus:
e=1

#42482 Re: Help Me ! » Tricky Puzzle » 2005-10-12 21:57:39

Let the pentagon be ABCDE
AB is 7,2,10
BC is 10,1,8
CD is 8,5,6
DE is 6,4,9 and
EA is 9,3,7

The total is 19 on all sides!

#42483 Re: Dark Discussions at Cafe Infinity » Wink Murder 4 » 2005-10-12 16:41:05

It was raining cats and dogs in Chennai yesterday evening. My murderer devised a novel method of eliminating me. He connected the water supply at my home to the power. When I opened the tap, I was hit by 230 Volts, enough to kill me!
Dead!

Now you know who the murderer is!

#42484 Re: Introductions » i hate subject fields. » 2005-10-12 16:37:44

Hi burrita,
Welcome to the forum.

#42485 Re: Guestbook » Austraila » 2005-10-11 20:27:37

I like Australia too.

australia-map.gif

#42486 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-10-11 20:22:13

Problem # k + 28

For any value of n (n∈N), prove that n²! is divisible by (n!)^n.

#42487 Re: Puzzles and Games » Make 28 » 2005-10-11 19:11:57

I don't know if its allowed:-
38 - (2 x 5)

#42488 Re: Help Me ! » algebra » 2005-10-11 16:36:21

Let the speed of Ben be x mph. Therefore, the speed of Alan is x - 0.6 mph. Their combined speed is 2x - 0.6 mph. This is equal to 11.4 miles divided by 3 hours. i.e.3.8 mph.
2x - 0.6 = 3.8,
2x = 3.8 + 0.6 = 4.4
x = 4.4/2 = 2.2
Therefore, the speed of Ben is 2.2 mph and the speed of Alan is 1.6 mph.

#42489 Re: Help Me ! » More Equations! » 2005-10-11 16:08:34

x = y + 30
y = 3z, z=y/3
Therefore, x + y + z = y + 30 + y + y/3 which is equal to 1500.
7y/3 = 1500 - 30 = 1470
y = 1470 x 3/7 = 630
y=630, x=660, z=210.

------------------------

Millie has 40 coloured shapes.

25 are circles and the rest are squares

23 of the shapes are blue and the rest are green

Therefore, 25 are circles and 15 are squares.

23 of the shapes are blue, therefore 17 are green.

The least number of blue circles is 8 and the least number of green circles is 2.

#42490 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-10-10 00:33:15

Problem # k + 27

What is the value of (1-Cos2A) / (1+Cos2A) given that tan A = 3/4 ?

#42491 Re: Dark Discussions at Cafe Infinity » Random Words » 2005-10-09 23:52:17


Serendipity

Osmosis

Catastrophe

Vigintillion

Connivance

Regicide

Thanatophobia

Mercenary

#42493 Re: Jokes » www.funcyber.com/good-free-jokes : joke site » 2005-10-09 18:00:19

The proper link is
www.funcyber.com/good-fun-jokes/.

Click here

I haven't seen the contents on the website yet, I have just provided the link.

#42494 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-10-09 16:48:15

Problem # k + 26

There are 2 brothers among a group of 10 persons. In how many ways can the group be arranged around a circle so that there is exactly one person between the two brothers?

#42495 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-10-09 16:38:49

You are right Mathsy. The solution to the problem given was 81.5, which is certainly incorrect! I would solve the problem exactly the way you did
(I thought of the method of solving at the time of posting, but didn't actually solve it!)

#42496 Re: Introductions » Hi » 2005-10-09 16:32:59

I forgot to mention...I think Kylekatarn is from Portugal too smile

#42497 Re: Help Me ! » Perfect Square Proof » 2005-10-09 16:31:22

A simple proof I can think of is
(a+b+c)²=a² + b² + c² + 2ab + 2bc + 2ac
When n=1 in your case,
a=10000, b=200, c=1
The resultant is 100000000 + 40000 + 1 + 4000000 + 400 + 20000 = 104060401.
This will continue as n increases.
For example, for n=2,
a=1000000, b=2000, c=1.
The resultant would be 1000000000000 + 4000000 + 1 + 4000000000 + 4000 + 2000000 = 1004006004001.
It can be seen that the other digits are not affected because of the number of zeros in a and b.
Hence, for any value of n, the resultant is a perfect square.
q.e.d

#42498 Re: Introductions » Hi » 2005-10-08 17:40:20

Hi frol....
I have a special place for Portugal in my heart, because I spent most of my childhood in Goa, India, earlier a colony of Portugal.
Here are some pictures of Goa....
st-cathedral-church-goa.jpg

goa_bom_jesus_church.jpg

dona-paula-goa.jpg

beach-dona-paula-goa.jpg

goa-beaches-india.jpg

#42499 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-10-07 23:19:39

Problem # k + 25

Three mathematics classes: X, Y, and Z, take an algebra test.
The average score in class X is 83.
The average score in class Y is 76.
The average score in class Z is 85.
The average score of all students in classes X and Y together is 79.
The average score of all students in classes Y and Z together is 81.

What is the average of all the three classes?

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