Stefan

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59 Answers

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9	How does $3^n-1+2 \cdot 3^n$ evaluate to $3^{n+1}-1$?
8	How does $2^{k+1} = 2 \times 2^k$?
6	Prove that $H=0$ or $H=\mathbb{Q}$
6	Derivative of $\arctan \sqrt x$
5	Why does $\bigcup_{X \in \mathscr{P}(\mathbb{N})}X = \mathbb{N}$, instead of $\mathscr{P}(\mathbb{N})?$

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1,554 Reputation

+10	Why is a real-valued inner product defined on a Euclidean space a continuous function
+10	If $A^2 = I$, $B^2=I$ and $(AB)^2=I$, then $AB = BA$
+20	Given $ 0 \neq f \in \mathbb C[x]$ prove that it has no double roots if and only if $gcd(f,f') = 1$
+10	Integrating $\frac{df}{f}$

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2 Questions

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2	Norm of operator $g\mapsto \int fg$
0	Show that $U \subset V \Leftrightarrow V^\bot \subset U^\bot$ for $U,V$ subspaces in a Hilbertspace

53 Tags

24 algebra-precalculus × 7	8 elementary-set-theory × 4
19 homework × 12	8 discrete-mathematics
17 linear-algebra × 8	7 calculus × 4
16 real-analysis × 8	6 derivatives × 2
10 abstract-algebra × 3	5 sequences-and-series × 3

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$Mathematics Stack Exchange$	Mathematics	1,554 rep	111
	Stack Overflow	151 rep	3

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