For questions related to usage of Wolfram Alpha.

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1
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2answers
71 views

Wolfram Alpha “x = derivative x”

Asking Wolfram Alpha $x = \text{derivative } x$, I was expecting $e^x$, being that the derivative of $e^x$ is $e^x$, Wolfram Alpha however yields $x = 1$. Is this stating that the derivative of a ...
-1
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1answer
53 views

Code Wolfram Mathematica [closed]

Sorry but I do not know English very well. The question is very simple, I hope someone knows the code that makes my case. In fact, writing: ...
2
votes
3answers
105 views

Did Wolfram|Alpha mess up $\int 1 - \frac{1}{1-e^{-x}} \mathrm{d}x$ or did I?

I want to calculate $$\int 1 - \frac{1}{1-e^{-x}} \mathrm{d}x$$ Provided that $x>0$. Substituting $u=1-e^{-x}$, we get: $$\int \frac{1 - \frac{1}{u}}{1-u} \mathrm{d}u = -\int \frac{1 - ...
1
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1answer
386 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 + ...
0
votes
1answer
204 views

Why is Wolfram Alpha wrong?

I calculated $$\tan 75^o - [\cot 13^o\cdot \cot 23^o \cdot \tan 31^o \cdot \tan 35^o\cdot \tan41^o]$$ and I got a nonzero answer: ...
2
votes
2answers
104 views

How does WolframAlpha solve quintic equations (5th degree polynomials)?

There exists no general formula for quintic equations. Then how does WolframAlpha solve quintic or higher degree polynomial. Is there a sure way to get values of roots of quintic or higher degree ...
3
votes
1answer
35 views

Simplify multinomial trig expansion to fewer linear terms like Wolfram?

I'm mystified as to how Wolfram Alpha's TrigReduce[expr] does its magic, particularly on sums of long products that look like $$A \cos^a(B_1 x) \sin^b(B_2 x) \cos^c (B_3 x) \sin^d (B_4 x) \dots$$ I ...
0
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1answer
68 views

Why can't Wolfram calculate the Laplace transform of $\sinh(t)\sin(t)$ correctly?

Question Show that the Laplace transform of $\sinh(t)\sin(t) = \frac{2s}{s^4+4}$. Wolfram can't calculate this as is, so I tried to simplify it a bit. I defined $\sinh(t)$ as $e^t-e^{-t}$ and split ...
3
votes
2answers
67 views

Plot of $y=x+0\sqrt{-x}$ (and WolframAlpha vs Desmos)

To plot the graph of $y=x+0\sqrt{-x}$ : Do we have to first find out the domain of $y$ which is $y \in ( -\infty,0 ]$ ? $\color{blue}{\text{[Case 1]}}$ (that's what I do) Or do we solve the ...
2
votes
2answers
88 views

Is Wolfram-Alpha giving me a wrong result?

I have to calculate: $$\nabla^2 \frac{e^{ikr}}{r}$$ which I know to be $\displaystyle -k^2 \frac{e^{ikr}}{r} $ (from a lecture). Doing it by hand: $$ \nabla^2 f(r) = \frac{1}{r^2} ...
1
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4answers
144 views

Is Wolfram Alpha calculating this incorrectly?

I entered in "does $2ln(x)$ equal $ln(x^2)$" into Wolfram and it came out false. Purplemath.com says that $log_b(m^n) = n · log_b(m)$. Which is correct? And why is there a difference?
3
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2answers
569 views

The sum of digits of $3(3x+3)$ is always $9$ for any $x$ between $1$ and $9$

Given the following 'joke' I stumbled across today It's easy enough to figure out that the answer is always 9. Asshole. However when I tried to 'prove' this for ...
0
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2answers
49 views

How to do multiplication (capital pi) in WolframAlpha?

How do i ask this in WolframAlpha: $$\prod_{i=0}^{i=10} \sin{(i)}$$ I used $\text{product}(...)$ and $\text{multiply}(...)$ or even $\text{multiplication}(...)$ but they don't seem to work. I am ...
0
votes
1answer
43 views

What function does Wolfram Alpha plot instead of the factorial?

Look to the second graph where Wolfram Alpha gives a continuous factorial function: What is the second graph? It is not the gamma function, since that has $\Gamma(-1)=0!=1$.
14
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7answers
2k views

Conflicting limit answers using calculator and wolfram alpha

I want to evaluate $\lim\limits_{x\to0} \dfrac{\tan(x) - \sin(x)}{(\sin(x))^3}$, Calculator says it's 0 when substituted with 0.0000000001. Wolfram Alpha says it's 1/2. The Problem Set says the ...
0
votes
3answers
94 views

WolframAlpha wrong(?) graph

I had a question to plot a graph of $\space \space\LARGE y=x^{x^{x^{x^{...}}}}$ Which (according to me) is equivalent to $\large y=x^y \Rightarrow y^{\frac{1}{y}}=x$ So i plotted them in ...
0
votes
1answer
80 views

Discrete Fourier Transform using WolframAlpha

I tried to verify a calculation with WolframAlpha. I want to compute the DFT of $[2,3,-3,1]$. So in particular one entry of the result vector should be $2+3-3+1=3$. I don't understand why I get ...
3
votes
2answers
146 views

Solving $\frac{dx}{dt} = A \frac{ (1-x)}{(t-t^2)} - \frac{(B*x -C*x^2)}{(t-t^2 )*(t-x)}$ (using wolfram/mathematica)

I would like to solve the following non-linear ordinary differential equation: $$\frac{dx}{dt} = A \frac{ (1-x)}{(t-t^2)} - \frac{(B*x -C*x^2)}{(t-t^2 )*(t-x)}$$ -I need an analytic solution. -I ...
0
votes
1answer
797 views

Priority of parentheses and brackets in basic arithmetic.

Wolfram alpha is giving inconsistent results to this problem: When I enter: 16÷2( 8-3(4-2) )+1 the result is 17. When I enter: 16÷2[ 8-3(4-2) ]+1 the result is 5. and 16÷2*[ 8-3(4-2) ]+1 brings ...
1
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2answers
51 views

Wolfram alpha giving wrong result on recurrence?

I have the recurrence$$a_{n+2}-a_n=1$$ The answer I got was $a_n=A+B(-1)^n+\frac n 2$, while WolframAlpha is giving me $a_n=A+B(-1)^n+\frac n 2- \frac 1 4$. Although when I plug them in the ...
2
votes
1answer
21k views

Taylor series expansion of arctan(x) around the point 0

This is actually a technical question about why I'm getting different results when trying to do the same thing using Maxima and WolframAlpha. When I enter expand arctan(x) in WolframAlpha I ...
1
vote
3answers
276 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 ...
2
votes
1answer
55 views

How to create animated plot of curve depending on parameter in WolframAlpha?

Is it possible to create in WolframAlpha an animated plot of a curve given by an equation, where some of the coefficients depend on the parameter (=on time)? For example if I would like to have a ...
2
votes
2answers
64 views

For what values of k is this singular matrix diagonalizable?

So the matrix is the following: \begin{bmatrix} 1 &1 &k \\ 1&1 &k \\ 1&1 &k \end{bmatrix} I've found the eigan values which are $0$ with an algebraic multiplicity of $2$ ...
0
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1answer
34 views

Plotting graph in Wolfram Mathmatica?

Which is the function that can plot me the graph K 7, 2 in mathematica? And after that to delete 2 edges?? Thanks for the help.
2
votes
1answer
34 views

How to find cubic residues $\bmod p$ using WolframAlpha?

How to find cubic residues $\bmod p$ using WolframAlpha? Just type in "quadratic residues modulo p" and you're done, but typing in "cubic residues modulo p" does nothing. Logically, "x^3 ...
1
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3answers
101 views

Why is Wolfram Alpha miscomputing this problem? [closed]

I was incorporating Wolfram Alpha into an API I am build, and to test it entered a few equations. One of the equations I entered was as follows. !6/(!3*!3) This ...
5
votes
1answer
117 views

Why does WolframAlpha give a strange solution set to $\lfloor a\rfloor=0$?

I decided to go and look up the roots of $\lfloor a\rfloor$ in WolframAlpha where $a$ is any number, real or complex, and of course the interval $[0,1)$ showed up as an answer but I also got these ...
7
votes
1answer
1k views

How do I plot multi case function in wolfram or geogebra?

How do I plot the following multi case function in wolfram or geogebra? $$ \begin{eqnarray*} f(x) = \begin{cases} 1, &\text{if }x \text{ is an integer}, \\ 0, &\text{if }x \text{ is ...
0
votes
2answers
726 views

How to solve this graph problem in WolframAlpha?

I need to input this problem in WolframAlpha: Write an equation of the line containing the given point and parallel to the given line: $(8,-8)$, $7x+8y=5$. The answer is $7x+8y=-8$ but I'm not ...
0
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2answers
89 views

Simplifying fractional exponents

I am very confused about the following: whenever I put in into wolfram alpha the answer it gives me is "indeterminate", is it not possible to simplify fractional exponents or something? if the ...
4
votes
2answers
101 views

Different results when integrating 1/(x^2-9) with computer tools

For checking my calculations, I generally use Wolfram Alpha or a similar tool. Today, I wanted to check the following integral: $$\int {\frac{1}{{9 - {x^2}}}} dx$$ From my calculations, using ...
1
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0answers
42 views

Fourier Tansform of derivative on Wolfram Alpha

If I'm not mistaken, the Fourier Transform of the nth order partial derivative of a function with respect to x, using the transform variable k is: (i*k)^n * [F(k)] so for the 1st order derivative ...
4
votes
2answers
64 views

Regarding $\lim \limits_{(x,y,z)\to (0,0,0)}\left(\frac{x^2z}{x^2+y^2+16z^2}\right)$--is WolframAlpha incorrect?

$$ \lim_{x,y,z\to 0} {zx^2\over x^2+y^2+16z^2}$$ So I am trying to evaluate this limit.. To me, by using the squeeze theorem, it seems that the answer must be zero. I trying using the ...
0
votes
2answers
76 views

Wolfram alpha integral

I want to evaluate the following integral in woflram alpha int[x e^(-lambda*(x-v)),{x,v,infinity} ] It doesn't work for some reason. It does work when instead of v, I put a number. For example ...
2
votes
2answers
57 views

What is the difference between $\ln(\sin\frac{x}{2}+\cos\frac{x}{2} )- \ln(\sin\frac{x}{2}-\cos\frac{x}{2})$ and $\ln(\tan x+\sec x)$

I've noticed if you ask wolfram what is the integral of $ \sec x$ they will answer $$\ln\left(\sin\frac{x}{2}+\cos\frac{x}{2}\right) - \ln\left(\sin\frac{x}{2}-\cos\frac{x}{2}\right)$$ I've been ...
16
votes
2answers
51k views

How to type logarithms in Wolfram|Alpha?

Its sometimes hard to type it if logarithm is not natural and base is not 10, especially if base is variable. So anyone know rules how to type?
2
votes
2answers
95 views

Wolfram Alpha result for infinite series summation .

Consider the infinite sum $s=1+1/2^2-1/3^2-1/4^2+1/5^2+1/6^2-...$. We can see that the series is absolutely convergent and hence convergent. But WolframAlpha seems to give me a different answer. When ...
0
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1answer
89 views

Recurrence Equation Solution / Difference equation - WolframAlpha

I am given the recurrece equation $y_k-7y_{k-1}=5^k$ and found the (hopefully correct) particular solution to be $y_k^P=-\frac{5}{2}5^k$ WolframAlpha, however, gives the particular solution ...
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2answers
114 views

Can wolframAlpha be wrong on this vector limit?

We had a homework on multivariable analysis, and there was this problem and the teacher said that we didnt trust wolfram but I'm not convinced on it, because of this. Is ...
1
vote
2answers
75 views

Handedness in Quaternion multiplication

I've received some code (which I didn't write) and decided at some point to write test cases for the Quaternion math implementation. I used Wolfram alpha to get the result q1 * q2, where: q1 = (4.0 ...
1
vote
0answers
42 views

Zeroes of the floor (greatest integer function)

I was just browsing Wolfram Alpha and looking at interesting graphs of functions when I noticed that it gave complex numbers for the numerical roots of $\lfloor x\rfloor$. Does anybody know why?
1
vote
1answer
44 views

Solve for Y; don't understand Wolfram Alpha's solution

Answering this StackOverflow question, I needed to solve this equation in terms of y: $$x = 6.1 + \log(\frac{{y}}{{0.03p}})$$ Doing it by hand: $$y = 0.03p10^{{(x-6.1)}}$$ Wolfram alpha tells me ...
1
vote
2answers
100 views

Name of special function used by Wolfram integrator

Integrating $e^{-r}/\sqrt{2t-r}$ with respect to $r$ between $r=t$ and $r=2t$ using this widget gives the answer $2e^{-t}F(\sqrt{t})$. However the widget doesn't say what $F$ is. I have looked on ...
6
votes
2answers
85 views

Calculate with sequences from OEIS

Is there any easy way to do calculations with sequences from OEIS online? For example I would like to input something like: (A007620(n+1) / 2 ) + A000027(n) and ...
0
votes
2answers
62 views

What are the limitations of modelling a piano sound with the 'play' option of the software Wolfram Mathematica?

'Play' is an input availabe on Wolfram mathematica, which shows how a wave would sound and I am asking myself what the limitations of this input are, in what aspects it does not represent 'real' sound ...
1
vote
1answer
81 views

stuck with a cubic equation

I picked an equation $0= x^3 +x^2 -2x -1$ I plotted it with geogebra, to see if it had more than $1$ real root. It definitely cuts the $x$-axis $3$ times. But when I checked wolfram alpha, to see ...
1
vote
2answers
244 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 ...
3
votes
2answers
58 views

Real integral getting numerically evalued to complex number

I tried feeding th following integral into WolframAlpha: $$\int_0^2\frac{1}{3\sqrt{x}(\log(x))^{\frac13}},$$ to get an idea of its value. Result: http://bit.ly/strangeint ...
10
votes
2answers
213 views

Proof that cos(1) is transcendental?

So, I was playing around on Wolfram|Alpha (as we nerds like to do) and it said cos(1) was transcendental. Could someone provide me with the proof that cos(1) is transcendental?