Guy

 15 Simple Proof of the Euler Identity $\exp{i\theta}=\cos{\theta}+i\sin{\theta}$ 8 Investigate convergence of $\sum_{n=2}^\infty \frac{1}{n(n-1)}$ 6 Convergence of $\sum\limits_{n=1}^\infty \frac {n+1}{2^n}$. 5 Proving that $f(x)=x^3+x+2$ is bijective without calculus 5 Semi-ring with isomorphic additive and multiplicative structure

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### Questions (11)

 8 Functional Equation $f(f'(x))=-f(x)$ 5 Basis in infinite dimensional Hilbert spaces 2 Fourier Coefficients of a Boolean Function 2 Determinant of sum of squares of commuting matrices 1 A Monoid and its Maximal Subgroup

### Tags (98)

 29 real-analysis × 14 15 education 23 calculus × 12 15 math-history 23 sequences-and-series × 8 11 ring-theory × 5 18 abstract-algebra × 9 11 galois-theory × 4 16 complex-numbers × 2 10 linear-algebra × 13

### Bookmarks (5)

 17 Prove that determinant of a matrix (with polynomial entries) is non-zero 11 Sequence $a_n = a_{n - 1} + a_{\lfloor n/2 \rfloor}$ 10 $\frac{1}{2^n}\binom{n}{n}+\frac{1}{2^{n+1}}\binom{n+1}{n}+…+\frac{1}{2^{2n}}\binom{2n}{n}=1$: short proof? 6 If $f^*:\mathrm{Hom}(H, R) \to \mathrm{Hom}(G, R)$ is an iso for all $R$, is $f: G\to H$ an iso? 1 Polynomial over local ring ( with finite residue field ) of Krull dimension $0$