User Sp3000

2 votes

Let $A= {x_0, x_1, · · · , x_m}$ be a subset of ${1, 2, · · · , n}$,where $m > n/2$,show that A contains two numbers b and c such that $x_0 + b = c$.

answered Sep 13, 2013 at 5:53

1 vote

Accepted

Boolean Algebra: Explain why (M AND (NOT N)) OR (X AND M AND N) = (M AND NOT N) OR (X AND M)?

answered Sep 13, 2013 at 4:58

1 vote

Finding the sum of two numbers given the difference of LCM and GCD.

answered Sep 13, 2013 at 2:55

2 votes

Mathematical Games suitable for undergraduates

answered Aug 8, 2013 at 12:41

2 votes

Need help with a simple math proof

answered Jul 3, 2013 at 3:52

2 votes

Combinations with exclusions

answered Jul 3, 2013 at 3:38

1 vote

Conversion Calculations

answered Jun 17, 2013 at 16:25

2 votes

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Solve : $x^2-92 y^2=1$

answered Jun 17, 2013 at 11:59

0 votes

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Optimal strategy for covering all possible subsets

answered Jun 13, 2013 at 9:11

3 votes

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Sum involving prime numbers

answered Apr 9, 2013 at 14:25

2 votes

Accepted

Looking for help with a lattice point graph problem.

answered Apr 9, 2013 at 14:21

9 votes

Pattern to last three digits of power of $3$?

answered Apr 9, 2013 at 12:53

2 votes

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Finding the last nonzero digit of $30^{2345}$

answered Dec 20, 2012 at 14:55

1 vote

How can I find the area of the region bounded by the hyperbola

answered Feb 8, 2012 at 1:38

9 votes

Odd-Odd-Even-Even Sequence

answered Feb 7, 2012 at 14:51

4 votes

Compute $\int_{0}^{\frac{\pi}{2}}\frac{\sin^2x\cos x}{\sin x+\cos x}dx$

answered Feb 7, 2012 at 10:30

1 vote

Dividing a picture into N number of equal parts

answered Feb 7, 2012 at 8:46

5 votes

Showing $24|(n+1)\implies24|\sigma(n)$

answered Jan 28, 2012 at 20:53

14 votes

Accepted

Lower bound for $\phi(n)$: Is $n/5 < \phi (n) < n$ for all $n > 1$?

answered Jan 23, 2012 at 14:34

3 votes

Solutions of some Diophantine equations

answered Jan 20, 2012 at 11:45

2 votes

Primes of the form : $x^2+4\cdot y^2$

answered Jan 6, 2012 at 10:08

2 votes

Which is the "fastest" way to compute $\sum \limits_{i=1}^{10} \frac{10i-5}{2^{i+2}} $?

answered Nov 12, 2011 at 16:23

4 votes

Accepted

Subsitution - integrals

answered Nov 11, 2011 at 1:38

2 votes

Proofs from the BOOK: Bertrand's postulate: $\binom{2m+1}{m}\leq 2^{2m}$

answered Nov 10, 2011 at 15:22

5 votes

How many triangles are there?

answered Nov 10, 2011 at 12:29

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25 Answers

Let $A= {x_0, x_1, · · · , x_m}$ be a subset of ${1, 2, · · · , n}$,where $m > n/2$,show that A contains two numbers b and c such that $x_0 + b = c$.

Boolean Algebra: Explain why (M AND (NOT N)) OR (X AND M AND N) = (M AND NOT N) OR (X AND M)?

Finding the sum of two numbers given the difference of LCM and GCD.

Mathematical Games suitable for undergraduates

Need help with a simple math proof

Combinations with exclusions

Conversion Calculations

Solve : $x^2-92 y^2=1$

Optimal strategy for covering all possible subsets

Sum involving prime numbers

Looking for help with a lattice point graph problem.

Pattern to last three digits of power of $3$?

Finding the last nonzero digit of $30^{2345}$

How can I find the area of the region bounded by the hyperbola

Odd-Odd-Even-Even Sequence

Compute $\int_{0}^{\frac{\pi}{2}}\frac{\sin^2x\cos x}{\sin x+\cos x}dx$

Dividing a picture into N number of equal parts

Showing $24|(n+1)\implies24|\sigma(n)$

Lower bound for $\phi(n)$: Is $n/5 < \phi (n) < n$ for all $n > 1$?

Solutions of some Diophantine equations

Primes of the form : $x^2+4\cdot y^2$

Which is the "fastest" way to compute $\sum \limits_{i=1}^{10} \frac{10i-5}{2^{i+2}} $?

Subsitution - integrals

Proofs from the BOOK: Bertrand's postulate: $\binom{2m+1}{m}\leq 2^{2m}$

How many triangles are there?