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Leyla Alkan

### Questions (101)

 11 Irrationality of $\pi^2$ and $\pi^3$ 9 a simple proof that $\pi$ is irrational by Ivan Niven 6 How to show $(\exists x)( \forall y)\varphi\rightarrow( \forall y)(\exists x)\varphi$ is logically valid 6 Stirling #s of 1st kind. Prove the following: $\sum_{k=0}^n S_1(n,k)x^k = x(x +1)···(x +n−1)$ 6 Stirling numbers of the first kind

### Reputation (1,538)

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 3 How many permutations of the word $STRESSLESSNESS$ begin OR end with an $E$? 3 How many different arrangements of the letters in “HYPERGEOMETRIC” begin and end with “E”? 2 Definite integral problem. I don't see a clear u-sub 2 Negation of uniqueness quantification in first-order logic 2 Solve the ODE $\cot (x^2+y^2)dy+xdx+ydy=0$

### Tags (84)

 6 permutations × 12 2 definite-integrals × 2 6 combinatorics × 10 2 quantifiers × 2 3 factoring × 4 2 ordinary-differential-equations 2 logic × 7 1 real-analysis × 4 2 first-order-logic × 5 1 polynomials × 4

### Accounts (19)

 Mathematics 1,538 rep 11 gold badge88 silver badges2424 bronze badges TeX - LaTeX 120 rep 66 bronze badges English Language & Usage 108 rep 44 bronze badges Physics 106 rep 55 bronze badges Cryptography 101 rep 11 bronze badge