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2d
comment To find the two dimensional subspace of $R^{3}$
(d) looks ambiguous: the variable $x$ is not quantified, and the variable $y$ does not appear in $(0,x,z)$.
Dec
18
revised Question about convergence of sequences
deleted 8 characters in body
Dec
11
revised Proof limit of sequence with square root
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Dec
11
comment Proof limit of sequence with square root
It is a limit of a composite function. We should learn what the OP knows, really.
Dec
11
reviewed Approve Old oxford scholarship question: $a^ab^b \ge a^bb^a$
Dec
11
answered Proof limit of sequence with square root
Dec
11
answered Proving that $\frac{u^p}{p}+\frac{v^q}{q}\ge uv$ under the condition $\frac{1}{p}+\frac{1}{q}=1$
Dec
10
revised Integration, substitution?
added 4 characters in body
Dec
10
revised Is zero positive or negative?
edited body
Dec
10
answered A concave positive function on $[1,\infty)$ is uniformly continuous
Dec
10
answered Can a sequence which decays more slowly converge?
Dec
9
comment Notation for intersection of functions
No, I always call it "the first intersection point of $f$ and $g$"...
Dec
9
comment Notation for intersection of functions
So do you mean $\inf (f-g)^{-1}(\{0\})$?
Dec
9
revised Using $q_A(x)=x^tAx$, the quadratic form associated with $A$.
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Dec
9
comment counterexample to strauss inequality
In any dimension $n \geq 2$, the inequality states that $$|U(x)| \leq C |x|^{(1-n)/2}\|U\|_{H^1}$$ for $|x| \geq 1$, where $U$ is a radial function. Hence $U$ must decay also for $n=2$.
Dec
9
revised How do I remove decimals from cent amounts?
added 4 characters in body
Dec
9
revised proving gradient of a function is always perpendicular to the contour lines
added 2 characters in body
Dec
9
reviewed Reject Help with $\int \frac{1}{(\sin x + \cos x)}$
Dec
9
awarded  Caucus
Dec
8
answered the Differential Equation $y'^2=y$