## Search found 151 matches

- Mon Mar 28, 2011 8:26 pm
- Forum: Higher Secondary Level
- Topic: minimum products needed
- Replies:
**0** - Views:
**1019**

### minimum products needed

Consider a sequence of $n$ nonzero numbers where at least one of them is positive. You are not allowed to see the numbers, but can know the sign of product of any two. Find, with proof, the minimum number of products you need to know if you want to determine the sign of every number in that sequence.

- Wed Mar 23, 2011 12:27 am
- Forum: College / University Level
- Topic: Injection from R2 to R
- Replies:
**4** - Views:
**6279**

### Re: Injection from R2 to R

There's one that maps all the points in $(0,1) \times (0,1)$ to $(0,1)$. Take $(0.a_1a_2a_3 ... ,0.b_1b_2b_3 ...) \rightarrow 0.a_1b_1a_2b_2a_3b_3...$. Such a map should work also

- Tue Feb 15, 2011 11:19 pm
- Forum: Physics
- Topic: simple pendulam in vacuam
- Replies:
**3** - Views:
**1749**

### Re: simple pendulam in vacuam

Motion of a simple pendulum is governed by gravity. So there is no reason that it will not oscillate in vacuum

- Mon Feb 14, 2011 2:16 pm
- Forum: Number Theory
- Topic: An easy to prove result about squares
- Replies:
**1** - Views:
**1133**

### An easy to prove result about squares

There are infinitely many non palidromic squares so that their digit-inverse (number formed by reading the number right to left) is also a square.

The result is wordy but the proof is verrrrry easy

The result is wordy but the proof is verrrrry easy

- Sun Feb 13, 2011 11:45 pm
- Forum: National Math Olympiad (BdMO)
- Topic: BdMO National Secondary (Higher Secondary) 2011/7
- Replies:
**8** - Views:
**3648**

### Re: BdMO National Secondary (Higher Secondary) 2011/7

Fahim, your

However, you should note one thing here (though I'm sure you are just good enough at recognizing it). For the completeness of the proof, you should also prove that friend of enemy and enemy of friend is an enemy. It seems trivial, but necessary.

*strange*proof is correct.However, you should note one thing here (though I'm sure you are just good enough at recognizing it). For the completeness of the proof, you should also prove that friend of enemy and enemy of friend is an enemy. It seems trivial, but necessary.

- Sun Feb 13, 2011 6:09 pm
- Forum: Social Lounge
- Topic: Math Books in Ekushey Boi Mela
- Replies:
**4** - Views:
**2024**

### Re: Math Books in Ekushey Boi Mela

The fair opens at 3 pm

- Sun Feb 13, 2011 9:04 am
- Forum: National Math Olympiad (BdMO)
- Topic: BdMO National Secondary (Higher Secondary) 2011/6
- Replies:
**7** - Views:
**3175**

### Re: BdMO National Secondary (Higher Secondary) 2011/6

Fahim, Well done. Your proof is correct.

- Sat Feb 12, 2011 11:45 pm
- Forum: National Math Olympiad (BdMO)
- Topic: BdMO National Secondary (Higher Secondary) 2011/6
- Replies:
**7** - Views:
**3175**

- Sat Feb 12, 2011 11:41 pm
- Forum: National Math Olympiad (BdMO)
- Topic: BdMO National Higher Secondary 2011/10
- Replies:
**3** - Views:
**2077**

### Re: BdMO National Higher Secondary 2011/10

There's a note about this problem-

This was one of the earliest problems of the question camp (might be even the first one). I like this problem very much, it is a beautiful one. One who solves it should appreciate its elegance as well.

This was one of the earliest problems of the question camp (might be even the first one). I like this problem very much, it is a beautiful one. One who solves it should appreciate its elegance as well.

- Sat Feb 05, 2011 10:43 pm
- Forum: National Math Olympiad (BdMO)
- Topic: BdMO 2011 National: Are you ready?
- Replies:
**8** - Views:
**2828**

### Re: Preparation for BdMO 2011 National

১) মাথা ঠাণ্ডা রাখ

২) মাথা ঠাণ্ডা রাখ

৩) মাথা ঠাণ্ডা রাখ

৪) কিছু প্র্যাকটিস কর

৫) পারলে আরো কিছু প্র্যাকটিস কর

২) মাথা ঠাণ্ডা রাখ

৩) মাথা ঠাণ্ডা রাখ

৪) কিছু প্র্যাকটিস কর

৫) পারলে আরো কিছু প্র্যাকটিস কর