dREaM
Reputation
33,550
95/100 score
 Aug 26 comment Average length of a cycle in a n-permutation do you count cycles of length $1$? Aug 26 accepted a matrix of rank $r$ satisfies a polynomial of degree $r+1$. Aug 25 revised Finding amounts of ingredients in a food based on nutrients deleted 2 characters in body Aug 25 comment Finding amounts of ingredients in a food based on nutrients Yes, sorry $v_1,v_2\dots v_{50}$ are linearly dependent, this is because there are more vectors than the dimension of the vector space, which is ten. I fixed it. Aug 25 comment A square matrix is called skew-symmetric if $A^T=-A$. Prove that if $A$ and $B$ are skew-symmetric matrices, then $A+B$ is skew symmetric. What have you tried? Do you know what the transpose is? Aug 25 revised Combinatorial Proof for Binomial Identity: $\sum_{k = 0}^n \binom{k}{p} = \binom{n+1}{p+1}$ added 2 characters in body Aug 25 answered Calculating some probability of buying different cards Aug 25 answered Combinatorial Proof for Binomial Identity: $\sum_{k = 0}^n \binom{k}{p} = \binom{n+1}{p+1}$ Aug 25 answered Finding amounts of ingredients in a food based on nutrients Aug 25 answered Ram shoots every third penalty to goal.If he gets chance to shoot all 5 penalty shots.What is the probability that he converts (does) exactly 3 goals. Aug 24 answered If $|xH|$ has order $n$, then there is an element $y$ with $|y|=n$ and $xH=yH$ Aug 24 comment Book on discrete mathematics for self study What do you mean Ragnar, do you mean an electronic version? Aug 23 answered $S$ is a non empty set and there are $a$ and $b$ for $c$ and $d$ such that $a\cdot c = d$ and $c\cdot b = d$, prove it is a group Aug 23 comment Seating people around a circular table (elementary counting technique) Yes, I agree with that. Nice approach by the way. Aug 23 answered Seating people around a circular table (elementary counting technique) Aug 23 answered What is the smallest prime $p$ such that the next prime is greater than $p+2000\$? Aug 23 comment What is the smallest prime $p$ such that the next prime is greater than $p+2000\$? @Peter I tried to do it for larger numbers but my system crashed :( Aug 23 comment What is the smallest prime $p$ such that the next prime is greater than $p+2000\$? The numbers seem to be large, for 220 the smallest primes are 122164747 and 122164969. I can't get past this :( Aug 22 comment A false conjecture by Goldbach I ran a computer program and 5777 seems to be the smallest number with that property, 5993 is the next. Aug 22 comment Is $S(a \cdot b)$ always less than $S(a) \cdot S(b)$ Sorry, the inequality is an equality if and only if $\sum_{l+k=j}a_ka_j$ is less than $10$. Thanks for noticing.