Reputation
12,400
Next privilege 15,000 Rep.
Protect questions
Badges
2 18 36
Newest
 Generalist
Impact
~69k people reached

1d
comment Formulate quadratic equation
Do you see any obvious roots? That is, try substituting some small numbers and see if you find a root. If you find a root $a$, then $r-a$ divides the polynomial, so you can reduce it to a quadratic.
1d
answered Compute a natural number $n\geq 2$ s.t. $p\mid n \Longrightarrow p^2\nmid n$ AND $p-1\mid n \Longleftrightarrow p\mid n$ for all prime divisor p of n.
1d
comment Multiplication of two successive Fibonacci numbers
Try using induction on $n$.
2d
answered limit of arctan
2d
answered How to solve the differential equation $y' + \sec(x)*y = \tan(x)$
Feb
9
comment Find the derivative of $y=\frac{\tan(x)}{1+\tan(x)}$
Just expand: $(1+\tan x)(\sec^2 x) = \sec^2 x + \tan x\sec^2 x$, and similarly for the other term.
Feb
9
comment Disjoint cycle Decomposition.
Have you tried actually writing out $\sigma^2$ and $\sigma^3$?
Feb
9
comment If $G/K$ is isomorphic to $H$ then is $G$ isomorphic to $KH$?
What do you mean by $KH$?
Feb
9
comment Is this identity about floor function true?
Working on Euler 546?
Feb
9
comment Define $\phi:\mathbb{R}^3 \rightarrow \mathbb{R}$ by $\phi(e_1) = 1$, $\phi(e_2) = 2$, $\phi(e_3)=-1$. Determine ker$\phi$ and im$\phi$
Can you write down a matrix for $\phi$? If you can, you should be able to use what you know to find the kernel and image of the map. To write down a matrix for $\phi$, you need to know what it does to an arbitrary element $(x,y,z)\in\mathbb{R}^3$; since it is linear and you know what it does to basis elements, this should be easy.
Feb
9
revised Find the recursive definition for the number of strings on 0, 1, 2 avoiding the substring 012?
added 863 characters in body
Feb
9
answered Find the recursive definition for the number of strings on 0, 1, 2 avoiding the substring 012?
Feb
9
answered Proof of 'Possibility of subtraction' from Apostol
Feb
9
comment On the existence of magic squares of every order different from $2$
It's not hard to see, just by setting up $2n+2$ homogeneous equations in $n^2$ unknowns, that there is a magic square with common sum $0$ if $n>2$. Adding a constant to each square then produces a magic square with a nonzero sum. It is not obvious (to me), however, that the elements can be chosen so that the entries are $1$ through $n^2$.
Feb
9
comment On the existence of magic squares of every order different from $2$
Yes. There are algorithms given here, for example.
Feb
7
answered Removing an edge from a circuit on a connected graph
Feb
7
comment Removing an edge from a circuit on a connected graph
Hint: The problem talks about removing an edge. The vertices that edge connects are not removed.
Feb
1
answered BMO2 2016 Number Theory Problem
Feb
1
comment find number of strings
Would the downvoter care to comment (@Arthur ?)
Jan
30
comment What is the min-max argument in mathematics?
Have you tried googling "minimax stochastic analysis"?