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age 56
visits member for 2 years, 6 months
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French math teacher. Some interest in combinatorics, cryptography, history and philosophy of sciences.


Jul
14
answered Books on rare techniques
Feb
14
comment How to solve $x^3 - 2x^2 -16x+16=0$?
Wolfram Alpha gives no nice solutions ....
Jul
14
answered Mathematicians talking about their identity as a person and as a mathematician?
Jun
7
comment Important numbers in Combinatorics
Genocchi numbers: en.wikipedia.org/wiki/Genocchi_number
Jun
3
comment How can I find the smallest possible of full miles to get full kilometers?
What a good idea it was to elaborate the metric system !
May
30
answered Pictorial puzzle
May
17
comment Sum of square root of primes
It's A062009 , with no other comment.
Mar
12
comment Solve $A_n=A_{n-1}+\lfloor \sqrt{A_{n-1}}\rfloor$
Maybe it helps if you see both equalities: $(m+k)^2+m-k+(m+k)=(m+k)^2+2m$ and $(m+k)^2+2m+(m+k)=(m+(k+1))^2+m-(k+1)$
Jul
31
comment Given a system of quadratic equations $x^2-a_ix+b_i=0$, can all of the coefficients $a_i$, $b_j$ be solution to one of these above equation?
Nice to see you come forward in this nice pb. Do you see now why $\sum {b_i} = 0$ and $\prod{a_i}=1$ come from ? (assuming each $b_i \neq 0$, it can be done without loss of generality after eliminating the solutions $\{x^2 - k_i x = 0 , i=1..n\}$) Don't forget in your study of the permutation on the set of equations, that it's possible to have many intricated cycles.
Jul
31
comment Given a system of quadratic equations $x^2-a_ix+b_i=0$, can all of the coefficients $a_i$, $b_j$ be solution to one of these above equation?
Nice to see you come forward in this nice pb.
Jul
30
revised Given a system of quadratic equations $x^2-a_ix+b_i=0$, can all of the coefficients $a_i$, $b_j$ be solution to one of these above equation?
added 33 characters in body
Jul
30
answered Given a system of quadratic equations $x^2-a_ix+b_i=0$, can all of the coefficients $a_i$, $b_j$ be solution to one of these above equation?
Jul
23
comment What will be the value of $P(12)+P(-8)$ if $P(x)=x^{4}+ax^{3}+bx^{2}+cx+d$?
And how do you prove that any other value for d gives the same answer ?
Jul
23
awarded  Critic
Jul
22
comment Roots with equal fractional parts
Isn't it, if m = n : $[(x-r)^n-a]-[x^n-b]$. So $r= 0$ and directly $a=b$.
Jul
11
answered Solve: $|-(x + 1)^2+1|\geq 1$
May
26
revised combinatorics: number of options to set a (a,b) ordered pair under terms
added 66 characters in body
May
26
answered combinatorics: number of options to set a (a,b) ordered pair under terms
May
13
answered What would be a good outdoor maths puzzle for children?
Apr
24
awarded  Supporter