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 Nov 29 accepted Finding the zero divisiors of $\mathbb{Z}_{n}$ Sep 30 accepted Prove that $2^n>n^4$ for all $n\geq 17$ Sep 29 accepted Cubic polynomial and its discriminant Sep 22 accepted Prove that $(\mathbb{R}\setminus \{0\},\sim):= ab>0$ is transitive. Sep 22 accepted Determine whether the function $\alpha:A\times B\rightarrow B\times A$ where $\alpha((a,b))=(b,a)$ is injective and/or surjective Sep 22 accepted Give an example of two functions $\alpha,\beta$ on a set $A$ such that $\alpha\circ\beta=\mathsf{id}_{A}$ but $\beta\circ\alpha\neq\mathsf{id}_{A}$. Sep 22 accepted Proving that $\alpha:\mathbb{R}\to\mathbb{R}$ where $\alpha(x)=\frac{x^{3}}{x^{2}+1}$ is bijective Sep 19 accepted Show that $A\setminus (B\setminus C)=(A\setminus B)\cup(A\cap B\cap C)$ Mar 4 accepted How do I design a generating function to count subsets of distinct objects? Feb 2 accepted How to tell if I am double counting in a combinatorics problem? Dec 17 accepted How does the triangle inequality work for $|x-y|$? Nov 4 accepted Finding the matrix of a linear transformation relative to two non-standard bases Oct 23 accepted What is an “incongruent” solution? Oct 14 accepted What is an intuitive definition of the zero vector? Oct 14 accepted Construct a basis for $\mathbb{R}^4$ given two vectors and any two of the standard basis vectors in $\mathbb{R}^4$ Oct 14 accepted Number theory GCD word problem Oct 14 accepted Can a matrix have a null space that is equal to its column space? Oct 14 accepted If matrices $B$ and $AB$ have the same rank, show that they have the same null spaces. Oct 14 accepted Prove that the Diophantine equation $ax+by+cz=e$ has a solution if and only if $(a,b,c)\mid e$. Oct 14 accepted Formally prove: $\lim_{n\to\infty}x_n=L_1\Longrightarrow\lim_{n\to\infty}x_{n+k}=L_1,\forall k\in\mathbb{N}$