For questions related to usage of Wolfram Alpha.

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0
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2answers
31 views

Polar graph inWolfram alpha

Maybe do you know wolfram alpha which draw graph Bu I cannot draw polar graph. For instance $$r=2\cos\ (t)\ : x^2+y^2=r^2=2r\cos\ t=2x\ (circle)$$ If we enter this, then it show $cosine$ graph, not ...
-1
votes
3answers
232 views

Symmetric matrix 10 x 10

Can You give me the example of symmetric matrix 10 x 10. Or if You know online symmetric matrix generator then give me the links. I tried to make this with Wolfram Mathematica but I did not find a ...
2
votes
1answer
64 views

The curve $(\cos(\sin x),\sin(\cos x))$ as plotted by Wolfram Alpha

I've just gotten this from Wolfram Alpha: It makes no sense to me. $\cos(\sin x)$ is never zero so how can this curve cross the $y$-axis?
2
votes
1answer
235 views

Computing 2d radially symmetric Fourier transforms (with Wolfram Alpha)

Let's assume that I "know" $\mathcal{F}\{\operatorname{circ}(r)\}(\rho)=\frac{J_1(2\pi\rho)}{\rho}$ $\mathcal{F}\{(1-r^2)\operatorname{circ}(r)\}(\rho)=\frac{J_2(2\pi\rho)}{\pi\rho^2}$ because I ...
1
vote
1answer
48 views

Wolfram Exponential Fit not match as formulas

I am using WolframAlpha Exponential-Fit formulas to find equation of Exponential Regression http://mathworld.wolfram.com/LeastSquaresFittingExponential.html but after implementation, I tested with a ...
0
votes
1answer
42 views

Problem with graphing a function.

To my understanding, function $f(x)=\frac{1+x}{1+x^3}$ should not be defined with $x=-1$ since: $f(-1)=\frac{1+(-1)}{1+(-1)^3}=\frac{1+(-1)}{1+(-1)}=\frac{0}{0}$ However, Google's plot drawer and ...
2
votes
1answer
129 views

Using newthon method to find nth root - did wolframalpha get it wrong?

I'm trying to implement the n-th root algorithm as outlined here: http://en.wikipedia.org/wiki/Nth_root My code however, takes a lot of iterations (more than 100) to converge. I tried to check with ...
0
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1answer
52 views

How does one provide a determinant as input to Wolfram Alpha?

$\begin{vmatrix} 17&-12&4&0\\ 5&9&-2&1\\ 3&-6&-1&14\\ 11&7&0&8\\ \end{vmatrix}$ How would one express the preceding determinant in the Wolfram Alpha™ ...
0
votes
0answers
212 views

What do Root[], #, & mean in Wolfram Alpha?

I wanted to find the roots of a particular equation by using Wolfram Alpha. What I get are strange answers. Thay look like this: What do all the symbols there mean and what does the whole thing mean? ...
0
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2answers
169 views

“Which is equivalent for restricted x values to”

I've been checking my homework via Wolfram Alpha, and for several questions (example below) in this section (trigonometric integrals). I'd be correct up until the last step, in which Wolfram Alpha ...
3
votes
1answer
105 views

What are these numbers?? (floor(a)=0)

I was just so I decided to go and look up the roots of floor(a) 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 ...
2
votes
2answers
68 views

Behavior of $f(x) = \sum_{n=1}^x \frac{1}{n}$

I plotted the function $$f(x) = \sum_{n=1}^x \frac{1}{n}$$ in Wolfram Alpha over $x\in\mathbb{R}$ and it gave me some unexpected behavior for negative $x$. This function is obvious for ...
1
vote
2answers
233 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 ...
2
votes
1answer
204 views

Can wolfram alpha compute symbolic vector derivatives

Can Wolfram alpha be used to find out say $$\nabla_x\left(\|y-Ax\|_2\right)$$ What command do I use? I tried some obvious ways, and googled a bit, but didn't find anything.
0
votes
3answers
121 views

Wolfram Derivation Error

I'm trying to derive the equation $$y = (2x-6)^4$$ I thought that it would be $$\frac{dy}{dx} = 8(2x-6)^3$$ Wolframalpha says $dy/dx = 64(x-3)^3$ Who's correct? I thought it would be a simple ...
1
vote
1answer
44 views

Please explain the steps in the solution of this integral

After unsuccessfully solving an integral, I turned to WRA for some guidance. Unfortunately, I don't understand what happen in the solution. More particularly, I don't understand why the numerator has ...
1
vote
1answer
47 views

Discrepancy over matrix exponential

I am trying to compute $\large e^A$ for $A = \left( \begin{array}{ccc} 0 & a \\ 0 & 0 \end{array} \right)$ Using $\large e^A = \sum \limits_{k=0}^\infty \frac{1}{k!} A^k$ Writing out the ...
0
votes
1answer
123 views

Why WolframAlpha gives different results?

Any idea why WolframAlpha gives different answers when computing the indefinite integral of these functions with respect to x first or with respect to y first? ...
10
votes
2answers
196 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?
6
votes
2answers
78 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
1answer
38 views

Help with creating formula

Lets say I have colony of 100 bacteria's. Within 1 year, each of bacteria brings up a "child" and becomes "infertile". After next year, children of bacteria bring up "children" and becomes ...
0
votes
1answer
64 views

Finding vertex of a parabola -conflicting answers

For a given problem $g(x) = 5x^2 - 2x +1$, we were expected to describe the graph. WolframAlpha and I are finding conflicting issues. I do not think I made an approximation anywhere that would explain ...
2
votes
1answer
34 views

Change linear plot to 100% plot in Wolfram Alpha

Recently I have used this input for WolframAlpha: Plot (forumla1), (formula2), (formula3), {a, 0, 50} It's generating "Linear Plot" like on picture on left. Is ...
1
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1answer
64 views

Analytic solution for the ODE $\frac{d y(x)}{dx}=\frac{a*y(x)^3+b}{c* y(x)^3+ d}$

I have an ODE $$ \frac{d y(x)}{dx}=\frac{a*y(x)^3+b}{c* y(x)^3+ d},$$ where $a,b,c,d$ are constants, and I would love to solve it analytically. I tried Maple 15 and 17 and got $$ y \left( x \right) ...
0
votes
1answer
84 views

What is DifferenceRoot?

In a question I asked earlier today in an effort to simplify the equation on the left below, I was pointed toward Wolfram Alpha. I got this back: I honestly have no idea what the right half of ...
1
vote
3answers
77 views

Trigonometric inequality bounded by lines

How can it be shown that $$16x\cos(8x)+4x\sin(8x)-2\sin(8x)<|17x|?$$ This problem arises from work with damped motion in spring-mass systems in Differential Equations. I have gotten to this ...
4
votes
3answers
193 views

Inverse Function (and WolframAlpha gives different Result)

I wanted to calculate the inverse function of $$ f(x) = \frac{1}{x} + \frac{1}{x-1} $$ Quite simple I thought, put $$ y = \frac{1}{x} + \frac{1}{x-1} = \frac{2x-1}{x(x-1)} $$ rearrange and solve $$ ...
1
vote
1answer
56 views

Calculating the eigenvalues of a given matrix, please check my results

Given the matrix $$A = \left(\begin{array}{ccc} 1&-0.85&0\\ 1.7&-1&0\\ 0 & 0.85 & 4 \end{array}\right)\in\mathbb{C}^{3\times3}$$ I am now looking for the ...
0
votes
1answer
230 views

Specifying complex domain in Wolfram Alpha

Hopefully this kind of question is ok, have seen a couple of other WA-queries that hasn't been downvoted. Apologies if not. I'm trying to find the max/min of a complex function over certain domains, ...
0
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2answers
155 views

Wolfram Alpha unexpected answer.

http://www.wolframalpha.com/input/?i=5+%2B+%286.7a%29%2B+%28a+%5E+0.8%29 What does "imaginary part" mean?
0
votes
3answers
416 views

Is Wolfram Alpha wrong with a simple derivative?

Let $f=\frac{x^2w(y-z)t}{18l}$ then (imho): $\frac{\partial{f(x,y,z)}}{\partial{w}}=\frac{x^2t(y-z)}{18l}$ However Wolfram Alpha produces a quite different result: Wolfram alpha result ...
1
vote
3answers
103 views

Derivative of $x^2-\frac{1}{x^2}$ not matching WolframAlpha result

I was calculating a very simple derivative of $$ f(x) = x^2-\frac{1}{X^2} $$ and my result is $$ f^{\prime}(x) = 2x + \frac{2}{x^3} $$ But I can't explain why WolframAlpha says the result is $2x$. ...
1
vote
2answers
119 views

How can these two be equivalent (wolfram-alpha incorrect) !?

So wolfram-alpha reads The integral of $$\int \frac{1}{\sqrt{a^2-x^2}}dx=\tan^{-1}\left(\frac{x}{\sqrt{a^2-x^2}}\right)$$ but that $$\int\frac{1}{\sqrt{a^2-x^2}}dx \;\mathrm{where}\; a=5 ...
1
vote
1answer
344 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 + ...
6
votes
1answer
144 views

Derivative of $\sec^{-1} e^{2x}$, my answer differs from wolfram alpha.

The problem: Find the derivative of $\sec^{-1} e^{2x}$ (\arcsec doesn't seem to work) My work: $u= e^{2x}$ $\mathrm{d}u = 2e^{2x}\,\mathrm{d}x$ The formula I know for the derivative of arcsec(u) ...
3
votes
0answers
691 views

How can I solve system of linear equations over finite fields in WolframAlpha?

Is it possible to solve system of linear equations over finite fields using Wolfram Alpha? If yes, how can I do that? Let us take a system $x+y+z=0$, $2x+y+2z=0$, $x+3y+z=0$. If I want to solve this ...
2
votes
2answers
4k views

Tell Wolfram Alpha that a variable is a natural number

how can I tell Wolfram Alpha that some variables are natural numbers, when I want to solve a equation? Cheers What I want to do: $\binom{n}{k}\cdot p^k \cdot (1-p)^{n-k} = \frac{1}{\sqrt{n\cdot p ...
1
vote
1answer
80 views

Inputting complicated equation into Wolfram

I am having a bear of a time getting this equation into Wolfram so I can solve it for E(r) = 1000. Everything is constant except for little r, which is the cursive r in each term. In case anyone ...
0
votes
2answers
57 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 ...
3
votes
1answer
2k views

Using Wolfram Alpha to solve a system of linear equations

How do I input the below system of equations in Wolfram Alpha in order to solve for the unknowns? I'm wondering if there's some kind of code that can be written in order to make wolfram alpha ...
0
votes
1answer
110 views

Solve equations in Wolfram with given variables

I am trying to use an equation as a template in Wolfram Alpha where the variables change. The equation is $-n = m - x\left\lbrack a - w\left(x - \frac{2l}{3}\right)\right\rbrack - w\left(x - ...
1
vote
0answers
57 views

hypothesis test and execution? did I do this right?

I am trying to figure this out and I'm not sure if I am doing it right. a) did I select the correct type of hypothesis testing??? b) am I using the numbers in the right place (I have SD for 3.5 for ...
2
votes
1answer
62 views

Wolfram-Alpha's choice of $k$ in a complex logarithm

I'm puzzling on this complex integral: $$ \int \frac{2ie^{it}}{2e^{it} - 1}dt = \log(2e^{it} -1)$$ The numerator is the derivative of the divisor, so the primitive is the log of the divisor. When ...
2
votes
2answers
123 views

WolframAlpha seems to suggest that $log(z) = log(-z)$

Wolfram-Alpha returns this snippet at the end of the "step by step solution": I'm confused by the negation of the expression inside the logarithm. The definition of complex logarithm is: $$log(z) ...
0
votes
1answer
994 views

Matrix math syntax in wolfram alpha

I'm having trouble getting Wolfram Alpha to do my bidding with regard to matrix manipulations. I am trying to take the derivative of the following matrix expression with respect to ...
1
vote
2answers
129 views

What is this question asking me? Help appreciated!

I was wondering if anyone would be able to help me understand what this question is asking me. How would I go about working these out on Wolfram Alpha? I'm not too sure how to input them. Any help is ...
2
votes
1answer
95 views

Is WolframAlpha computing this radical correctly?

Is WolframAlpha computing this radical correctly? $$\sqrt{\frac{1}{1 + {10}^{-375}}}$$ When I double-check again, the inequality: $$\sqrt{\frac{1}{1 + {10}^{-x}}} > 1$$ leads to a ...
0
votes
1answer
2k views

Label x axis in radians WolframAlpha

I am trying to graph a trig function in WolframAlpha. I want the x axis to show radians. It will do this for a basic function, such as $y=\sin x$, but for many functions it will just label the x axis ...
1
vote
2answers
304 views

Falling/Rising factorials on WolframAlpha

Is there any notation to input falling or rising factorials on WolframAlpha?, the site has info about but i cant find nothing more.
0
votes
1answer
380 views

How to solve this linear set of equations using W|A?

I try to solve a simple system of four linear equations in the variables ch1, ch2, co1 and co2: ...