Questions tagged [question-verification]
This tag is for checking the validity of a question or a problem
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Is this a valid vector space? (Question Verification) [closed]
Hi - please see the question above. I have a problem with proving associativity i.e. that $(\alpha \beta)v = \alpha(\beta v)$ where $\alpha, \beta \in \mathbb{R}$ and $v \in \mathbb{R}_+$.
I think ...
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A question in Strauss PDE exercise 9.4.2
In chapter 9.4 of Strauss PDE, we try to find the solution of 3D Diffusion Equation. And there is a exercise which is closely relating to the proof, as following:
$$\lim_{t\to0} \iiint_{R^3} S_3(X-X',...
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Circuit Probability Question from Mathematical Statistics
From Mathematical Statistics, 7th ed., Chapter 2, Supplementary Exercise no. 2.163:
Relays used in the construction of electric circuits function properly with probability $0.9$.
Assuming that the ...
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At most A does not occur
Let $A$ and $B$ be two events in the sample space $S$. Describe & represent the following event in terms of $A$ and $B$: "at most $A$ does not occur".
This is a question that someone ...
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Null sets cannot be covered by intervals for sufficiently small $\epsilon$ [closed]
I was trying the prove the following statement (Folland 1.5.30):
If $E\in\mathcal{L}$ and $m(E)\gt0$, for any $\alpha\lt1$ there is an open interval $I$ s.t. $m(E\cap I)\gt\alpha m(I)$.
The easiest ...
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Extension of C1 functions
I studying the extension problem for classes of function $C^0,C^1,D^1$ ($D^1=$class of derivable function).
For $C^0$ function there is Tietze theorem and for $D^1$ function there is Jarnik theorem (...
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How do I check if this number is transcendental?
Two days ago, I tried to create an infinite series that might be able to generate a transcendental number, and when I checked the proper definition, it was mentioned that, it is a number that cannot ...
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Calculating the area enclosed by three graphs, but two out of them already enclose a different area.
I have three functions :
$$y = 2x^2 + 2x \tag{1}$$
$$y = -x - 1 \tag{2}$$
$$x = 0 \tag{3}$$
Exercise asks for the area enclosed by three of those functions.
It is clear that the area from $x = \frac{-...
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Two variable functions and continuity
Since
$$\lim_{(x,y)\to(0,0)}\frac{x^4-y^4}{x^2+y^2}=\lim_{(x,y)\to(0,0)}\frac{(x^2+y^2)(x^2-y^2)}{x^2+y^2}=\lim_{(x,y)\to(0,0)}(x^2+y^2)=0$$
and
$$\lim_{(x,y)\to(0,0)}\frac{x^4}{x^2+y^2}=\lim_{(x,y)\...
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Are these test paper questions as unclear and ambiguous as I think they are?
The Local Education Authority here in Wales are running a free voluntary course online for maths dunces like me to help us to help our 7-14 year olds with maths.
There's a free optional paper leading ...
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What does c mean in the following question on cardinality?
I found a question in Modern Real Analysis by William P. Ziemer. The question can be found in Section 2.1 Question 1. It goes:
Use the fact that $\mathbb N =$ {$ n: n = 2k$ for some $k \in \mathbb N$} ...
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If $x^2+bx+a=0, x^2+ax+b=0$ do not have distinct real roots then find the maximum value of $\frac{a^2+b^2}{a+b}$ if $a,b\gt0$
If $x^2+bx+a=0, x^2+ax+b=0$ do not have distinct real roots then find the maximum value of $\frac{a^2+b^2}{a+b}$ if $a,b\gt0$
Solution:
$D\le0\implies b^2-4a\le0, a^2-4b\le0$
It implies $b^2+a^2\le4(...
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Something's not right about my understanding about identity matrices.
I tried the following problem.
Let $A = \begin{bmatrix} \alpha & 0 \\ 0 & \beta \end{bmatrix}$ and $B = \begin{bmatrix} 0 & \gamma \\ \delta & 0 \end{bmatrix}$.
There are 2 statements:
...
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Max number of emails processable by consumer of email server
I saw this statement awhile ago, and I'm bit confused about how it works.
Suppose you have an email server that can only receive 3 emails every minute, and additional emails are filtered out. (Aside: ...
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Finding the equation of a circular cylinder
I need to find the equation of the circular cylinder whose generators are parallel to the line $x=y=z$ whose guiding curve is the circle:
$$x^2+y^2+z^2-2x-3=0, \ \ 2x+y+2z=0 $$
My approach I assumed ...
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