For questions related to usage of Wolfram Alpha.

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1
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1answer
19 views

Vertex Cosine Similarity of a weighted graph

I'm trying to calculate the vertex cosine similarity of a weighted directional graph, however struggling to understand the concept. While I understand the methodology for simple and directed graphs, ...
0
votes
0answers
18 views

Wolframalpha, picturing sets

I have a short question. Is there a way to picture sets like $\{z+2\pi k+i, k\in\mathbb{Z}, z\in S^1\}\subset\mathbb{C}$ with wolframalpha, or any other online tool? Thanks in advance.
1
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0answers
44 views

How to graph 3D functions of two variables on Wolfram Alpha?

How to graph this on wolfram, google, or other free software: \begin{alignat*}{3} x(s, t) &= a\cos(mt) \cos^{k}(ns) &&\cos(t) &&\cos(s), \\ y(s, t) &= a\cos(mt) \cos^{k}(ns) &...
2
votes
1answer
36 views

Why does Wolfram show two different medians for this dataset?

If you enter these values into Wolfram: {18,21,13,19,24,17,14,12,15,14} In the Statistics output it shows a median of 16, which is correct. However, in the Box ...
1
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1answer
539 views

Newton backward interpolation in Mathematica

I have the following task: Create a function (in Wolfram Mathematica), called $\mathrm{NewtonBackward}$[n_,x0_,h_,f_] which interpolates backwards the function $f(x)$ with nodes {x_i = x_0 + $i$$\...
1
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2answers
47 views

Confused About Equation Rearrangment

Full disclosure; I have a very very basic understanding of higher math. I apologize if this is stupid / has been answered. I don't really know how to even format my question. I have a formula used in ...
2
votes
3answers
97 views

Is the solution from wolfram alpha for $x^4+bx^3+f=0$ only wrong for $b=0$?

edit, tldr: it seems like the question is interpreted as "for which combinations of a and f is there a solution to the expression"? I'm only interested in "for which combinations of a and f is the ...
1
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5answers
57 views

Represent $50+49+48$ and so on to zero

How do I mathematically represent the operation of adding $50$, for example, to continuous decrements by $1$ until we reach $0$ ? $50+49+48+47+\dots$ until we reach $0$. For example, how do I put this ...
0
votes
1answer
26 views

Lerch Transcendent Notation and Definition

I used Wolfram-Alpha to try to find the sum $$\sum_{n=0}^\infty (-1)^n\ln\frac{n+2}{n+1}.$$ While it only gave a numerical result, it showed the partial sum formula included $\text{LerchPhi}^{(0,1,0)}...
1
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0answers
28 views

Does y = 2 + 0(1/(x-2)) contain a hole? Seemingly no?

Out of curiosity, I typed the equation y = 2 + 0(1/(x-2)) into wolfram alpha to find that it simplified it to y = 2. Is this correct? I assumed there would be a hole or some lack of continuity at x = ...
0
votes
0answers
38 views

Why is the infinite series of 0^n divergent?

No lie, Wolfram Alpha just told me it is. My input was "sum from 1 to infinity of 0^n" and its output was "By the geometric series test, the series diverges", but without interpreting as a geometric ...
2
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3answers
358 views

WolframAlpha function that returns the 'decimal' part of a number [closed]

Is there a function or command in Wolfram Alpha for getting only the decimal part of a number? Something like this: DecimalPart(3.4231) = 0.4231 I will be using ...
0
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2answers
61 views

How do I include an integer constraint in Wolfram Alpha?

Related question: Tell Wolfram Alpha that a variable is a natural number I want to do the following in Wolfram Alpha: Minimise $$z = (y_1-x_1)+(x_2-y_2)+(1/2)(x_3)$$ s.t. $$0 \le ...
0
votes
1answer
25 views

What is wrong with my Boolean expression?

I've got the following expression: A*!B*(!B*C+!C*A*(D+B*!A+D*A*B+C*!D)) After translating it to Wolfram's understandable language I got this: ...
0
votes
1answer
68 views

What is the result of this infinite sum?

I'm trying to find the value of $\mathbf S$ where $$\mathbf S = \sum_{k=1}^\infty \frac{\sin(2\pi k x)}{k}; k \in \mathbb N, x \in \mathbb R^*, x \not \in \mathbb N$$ I had a look to WA which lead ...
1
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1answer
20 views

Does this Diophantine inequality have any solutions for $p, q \in \mathbb{N}$?

Does this Diophantine inequality have any solutions for $p, q \in \mathbb{N}$? $$p^2 q^2 \geq 3 p^2 q + 3p^2 + 3pq^2 + 3pq + 3p + 3q^2 + 3q + 3$$ I tried to use Wolfram Alpha, and it says that ...
1
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3answers
67 views

$0^0$ is undefined, but sometimes defined as $1$?

When typing a calculation to Wolfram Alpha it always takes $0^0$ as undefined, but for some calculations I need to preform, I specifically need it to be equal $1$. Is there a way to make it ...
0
votes
1answer
27 views

True or false under several conditions [closed]

I want to check whether $$\max\bigl(0, x+\max(0, y+z-1)-1\bigr)=\max\bigl(0, z+\max(0, x+y-1)-1\bigr)$$ under restriction $x,y,z\in[0,1]$ but I don't know how to type it in WolframAlpha. For example ...
1
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0answers
60 views

Fourier Tansform of derivative on Wolfram Alpha

If I'm not mistaken, the Fourier Transform of the $n$th order partial derivative of a function with respect to $x$, using the transform variable $k$ is: $$(i*k)^n * [F(k)]$$ so for the $1$st order ...
-1
votes
2answers
60 views

Plot the solution curves of $\frac {dx} {dt} = - xe^{-x^2}$

Plot the solution curves and phase portrait of $$\frac {dx} {dt} = - xe^{-x^2}$$ It seems that it's increasing for $x < 0$ and decreasing $x > 0$. Then it seems concave down for $\frac {-1} {\...
6
votes
3answers
1k views

Why is wolfram alpha plotting this differently?

I have an equation for a cylinder as $x^2+(y-b)^2=a^2$ for some $a$ and $b$. so I just plugged in $b=2$ and $a=1$ and tried to plot it using wolfram alpha, and the 3D plot looked like half a cylinder, ...
4
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1answer
69 views

Integral of $\dfrac{1}{x\sqrt{x^2-1}}$

I am very confused by this. I know that the derivative of $\text{arcsec}(x)$ is $\dfrac{1}{|x|\sqrt{x^2-1}}$. However, if you plug in the integral of $\dfrac{1}{x\sqrt{x^2-1}}$ into wolfram alpha it ...
0
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1answer
34 views

Plotting numbers in the complex plane using WolframAlpha

I read this article on understanding imaginary numbers as rotations of real numbers in the complex plane. Having read it, it's easy for me to see how the real number $1$ is simply a point on the real ...
0
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0answers
14 views

Two variants of Radiality centrality

I am implementing Radiality centrality. For formula I am using definition from CentiScaPe: Network centralities for Cytoscape. I was doing some tests and I found some examples at Wolfram Alpha site. ...
0
votes
0answers
39 views

use of wolfram in determining area between two curves

I am new to the use of Wolfram (that for the limited cases I have used is very impressive). However I wonder if anyone can tell me what I am doing wrong. I wanted to calculate the area between the two ...
0
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4answers
81 views

Is $x=0$ a local minimum of $f(x)=x^{2/3}(5-x)$?

It seems to be decreasing for values below zero and increasing for values between zero and 2. However $f'(0) = \frac{(-5 (x-2))}{3 x^{1/3}}|_{x=0}$ does not exist. So it's not a local minimum? Btw, ...
1
vote
1answer
27 views

Problem Inputting Formula Into Wolfram Alpha [closed]

I am trying to calculate the following: $1-\sum_{k=0}^4\frac{\binom{2,500}{k}\binom{247,500}{8,500-k}}{\binom{250,000}{8500}}$ I am inputting this into wolfram alpha like this but I can't seem to ...
14
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6answers
30k views

cubic root of negative numbers

Excuse my lack of knowledge and expertise in math,but to me it would came naturally that the cubic root of $-8$ would be $-2$ since $(-2)^3 = -8$. But when I checked Wolfram Alpha for $\sqrt[3]{-8}$, ...
0
votes
1answer
15 views

PrimeQ[ Table[sum_(n=1)^(N)n!, {N,1,30}]]

The PrimeQ[Table[...]] command used to work in Wolfram|Alpha back in 2012 but now it doesn't give any answer. Is there a substitute?
0
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1answer
32 views

Partial derivative of $\frac{d}{dx}(x^2-2sin(y))$

WolframAlpha computes $\frac{d}{dx}\left(x^2-2(\sin y)\right)$ to be $$ \frac{d}{dx}\left(x^2-2 (\sin y)\right) =2 \left(x-(\cos y)y'(x)\right) $$ entered "differentiate (x^2 - 2*sin(y)) with ...
0
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0answers
30 views

Evaluating a sum on binomial coefficients

I'm reading Casella's and Berger's Statistical Inference. On page 239 they gives a claim that $$\sum_{x=0}^{330}\binom{300+x-1}x\left(\frac{1}{2}\right )^{300}\left (\frac{1}{2}\right )^x\approx 0....
1
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1answer
41 views

Relations between hypergeometric functions

I am trying to find a relation between hypergeometrics $${}_2F_1(a,b,c;z)\,\,\text{and}\,\,{}_2F_1(a+1,b+1,c+1;z)$$ I can see that $$\frac{\partial}{\partial z}{}_2F_1(a,b,c;z) = \frac{ab}{c}{}_2F_1(...
0
votes
1answer
49 views

Two results for the same (?) derivative $f(x) = \frac{y}{x}$

I was looking for a method to differentiate $f(x) = \frac{y}{x}$. Entering "differentiate $f(x) = y/x$" into WolframAlpha gives result: $$ f'(x) = \frac{-y}{x^2} $$ The main step of computing this ...
1
vote
3answers
280 views

Evaluation of the integral $\int_{-6}^{-3}\frac{\sqrt{x^2-9}}{x}$

How to evaluate the following integral? I have tried the following things but I have no idea to continue after the last step. Moverover, the integral seems wrong when compared with the ans from ...
0
votes
1answer
78 views

Is wolframalpha wrong (Plotting inequalities)

I just wanted to plot a simple inequality: $$-x \geq 4$$ and wolframalpha gives me the following plot: But I think it should look like this: Am I correct? If so why is wolframalpha producing such ...
1
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2answers
40 views

Residue at infinty, contradiction?

I am trying to find the residue at $z=\infty$ of the function $$f(z)=\frac{z^4}{\sqrt{z^2-1}}$$ This has a Laurent series about $\infty$ of: $$f(z)= Z^3+ \frac{1}{2}z+\frac{3}{8}\frac{1}{z}+\frac{5}{...
1
vote
3answers
53 views

How do I tell Wolfram Alpha that I want the fourth derivative of y in a differential equation?

For example, how would I enter y^(IV) - 16y = 0? typing out fourth derivative, and putting four ' marks does not seem to work.
0
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1answer
46 views

Wolfram Alpha Step By Step For Systems of differential equation

Does anyone know if wolfram alpha has step by step solutions for systems of differential equations? When I input them, it comes up with an answer but it does not give me the step by step solution. I ...
6
votes
4answers
167 views

How many values does $\sqrt{\sqrt{i}}$ have?

Wolfram says, there are only two roots, but $\sqrt{i}$ already gives two roots. So if we express them in Cartesian form we can take square roots of them separately and end up with four roots. $$\sqrt{...
1
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2answers
22 views

Integral of $-4\sin(2t - (pi/2)) $ weird behavior on wolfram alpha

I'm confused by what Wolfram Alpha is doing with my function: $$-4\sin{(2t - (\pi/2))}$$ on why the it gets replaced by $$4\cos{(2t)}$$. Is it equal? Link: See behavior here
3
votes
1answer
65 views

Repeating decimal notation of 1/53 on WolframAlpha vs notation on Wikipedia

WolframAlpha shows for 1/53 $0.0\overline{1886792452830}$ as the repeating decimal. Why is it not $0.\overline{0188679245283}$ instead? For example, Wikipedia shows for 1/81 $0.\overline{...
7
votes
2answers
628 views

A ''strange'' integral from WolframAlpha

I want integrate: $$ \int \frac{1}{\sqrt{|x|}} \, dx $$ so I divide for two cases $$ x>0 \Rightarrow \int \frac{1}{\sqrt{x}} \, dx= 2\sqrt{x}+c $$ $$ x<0 \Rightarrow \int \frac{1}{\sqrt{-x}} \, ...
0
votes
0answers
13 views

Inserting “holes” on a graph.

I am trying to plot the set $A = \big\{(x,y) \in \mathbb{R}^{2} \mid x^{2} + y^{2} < 2 \big\} - \big\{(0,\frac{1}{n}) \mid n=1,2,3 \dots \big\}$. I have tried different combinations of set ...
1
vote
3answers
626 views

Why does Wolfram Alpha say that $n/0$ is complex infinity?

I typed a number divided by 0 on Wolfram Alpha and thought that it would say "undefined". However, when I pressed enter it told me that the answer is complex infinity. I have always been taught ...
1
vote
0answers
56 views

Maple and WolframAlpha return different results

I solved the integral of u/(1-u) by hand and found as result -ln(1-u) - u + constant. Now, when I evaluate this integral with WolframAlpha, I get the same result. But when I evaluate it with Maple, it ...
7
votes
3answers
4k views

Derivative of floor function

I thought the derivative of function $\text{floor}(x)$ should be $\infty$ for integer values of $x$ and 0 elsewhere. But wolframalpha plot showed something different. Is there any explanation?
1
vote
0answers
35 views

Application of Initial Value Theorem

Let $$F(s):=\frac{s}{2s-i}$$ be the Laplace transform of some $f(t)$. I have been asked to compute $f(0^+)$ assuming that this quantity, intended as limit, exists. I thought I could apply the IVT ...
0
votes
2answers
47 views

Calculating limits with Wolfram|Alpha

in a random graph setting with $n$ vertices and edge-probability $p$ I want to show that $\binom n4p^6\to 0$ as $pn^{2/3}\to 0$. To check this is even true, I submitted this Wolfram|Alpha query. Now ...
0
votes
2answers
38 views

About a solution in Wolfram Alpha

I'm intrigued by this finding on the extraordinary portal WolphramAlpha. What is the reason why the solution has not been simplified, eliminating the factor $\frac{\sqrt x \sqrt{x+2}}{\sqrt {x(x+2)}}...
0
votes
0answers
66 views

Solid has same volume when axis of rotation increases?

I'm working on calculating the volumes of different solids using integration. The problem I'm working on says to find the volume of two solids, one revolved around the line $x = 4$ and the other ...