Feb
2
answered Numerical puzzle
Feb
1
revised When does the equation $a^n \equiv n \pmod m$ has exact one solution with $1\le n\le m-1$?
tex
Feb
1
answered With a product and sum of $x$ and $y$, calculate $9x^2+15y^2$
Feb
1
comment With a product and sum of $x$ and $y$, calculate $9x^2+15y^2$
@Piwi: This problem differs from the problem you are refering to. $9 x^2+15 y^2$ is not a symmetric polynomial.
Feb
1
comment Prime number test and Fermat's little theorem
@lab bhattacharjee: yes, that is the same as saying "$a^{p-1} \equiv 1 \pmod p$ if $p$ is a prime"
Feb
1
revised Prime number test and Fermat's little theorem
typo
Feb
1
comment Prime number test and Fermat's little theorem
$a^{p-1} \equiv 1 \pmod p$ if $p$ is a prime: en.wikipedia.org/wiki/Fermat's_little_theorem .But there are none primes such that the equation holds, like $341=11 \cdot 31$.
Feb
1
comment Coin flipping probability game ; 7 flips vs 8 flips
@David Richerby: You are right, I misread the OP. I will destroy my comment
Jan
29
comment How can i quickly calculate an approximation of $\sqrt[5]{192}$ with just pen and paper
Without comparing the results to the value calculated by a calculator: Which answer gives the approximation of $\sqrt[5]{192}$ to one digit?
Jan
27
answered Given $x+y$ and $x\cdot y$, what is $x^3+ y^3$ ?
Jan
27
comment Relative error machine numbers
I got the following relative errors for method A, B with $a$ and $b$ machine numbers and method A and B for $a$ and $b$ no machine numbers. But maybe I did some mistakes. $$3 \xi$$ $$\left({{b^2+a^2}\over{\left| b^2-a^2\right| }}+1\right)\xi$$ $$\left({{\left| b\right| +\left| a\right| }\over{\left| \left| b\right| - \left| a\right| \right| }}+4\right)\xi$$ $$\left({{3\,\left(b^2+a^2\right)}\over{\left| b^2-a^2\right| }}+1\right)\xi$$
Jan
26
answered Relative error machine numbers
Jan
26
revised Diophantine equation in two variables.
grammar
Jan
26
comment Find intersection of 2 parameterized planes
$\{u_1,0,v_1\}$ and $\{u_2-1,v_2-1,1\}$ and now equate the terms. $u$ and $v$ represent arbitrary real values in a term but not the same in both terms.
Jan
25
revised When does $\cos\frac{\pi}{m}=2\cos\frac{\pi}{r}\cos\frac{\pi}{n}$ with $m,n,r \in \mathbb{Z}$ hold?
typo
Jan
25
answered Solve the error in the simultaneous equation.
Jan
23
revised How do I go about algebraic manipulation of polynomials with many terms?
an additional sentence
Jan
23
revised How do I go about algebraic manipulation of polynomials with many terms?
typo
Jan
23
comment How do I go about algebraic manipulation of polynomials with many terms?
the leading term is $6n^5$ on the lhs but $4n^5$ on the rhs. The constant term is $1$ on the lhs and $-1$ on the rhs. Your equation still does not hold.
Jan
23
revised How do I go about algebraic manipulation of polynomials with many terms?
some tricks