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Mathematics
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crskhr

Our true needs are deeper, yet in our modern society most of us reflexively and relentlessly pursue wealth, consumer goods and admiration. We have learned from Perelman's mathematics. Perhaps we should also pause to reflect on ourselves and learn from Perelman's attitude towards life : William Thurston

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18 How can I show that $\begin{pmatrix} 1 & 1 \\ 0 & 1\end{pmatrix}^n = \begin{pmatrix} 1 & n \\ 0 & 1\end{pmatrix}$? Sep 20 '13
14 How does one evaluate $\int \frac{\sin(x)}{\sin(5x)} \ dx$ Oct 19 '14
12 If $f(1)=1$, then is it true that $f(n)=n$ for all $n \in \mathbb{N}\cup\{0\}$. Oct 4 '17
12 Prove: $\sin (\tan x) \geq {x}$ Jan 18 '14
11 Find the value of: $\sum_{n=1}^{50}n(n!)$ May 1 '15
10 How to show $\sum_{k=0}^{n}\binom{n+k}{k}\frac{1}{2^k}=2^{n}$ [duplicate] Jul 29 '16
10 Is $\left( {{2}^{x}}-1 \right)\left( {{5}^{x}}-1 \right)$ a square number for integer $x>1$ Jul 24 '18
9 Alternating sum of binomial coefficients multiplied by (1/k+1) Oct 8 '14
8 Sum of $50$ terms of $\cot^{-1}3+\cot^{-1}7+\cot^{-1}13+\cot^{-1}21+…$ Dec 15 '18
8 How to calculate $\lim_{x\to0} \frac{\ln(1+x)+\ln(1-x)}{x^2}$? Nov 1 '17
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