For questions related to usage of Wolfram Alpha.

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0answers
24 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? ...
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2answers
15 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
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1answer
70 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
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2answers
56 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 ...
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1answer
70 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
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1answer
63 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.
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3answers
109 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 ...
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3answers
59 views

How to solve that kind of equation using Wolfram Mathematica? [closed]

I need to find all variables $$A, B, C, D$$ for given equation with independent variable $$s$$ How can Mathematica solve that? Example, not working: UPDATE: One Two Three Four ...
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1answer
38 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 ...
0
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0answers
87 views

Wolfram and solids of revolution

I'm looking for the easiest method of having WolframAlpha calculate the volume of a solid of revolution. I've been working on a particular Project Euler problem for a long time. So far, I think I ...
1
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1answer
37 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 ...
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1answer
75 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? ...
0
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0answers
30 views

How are massive parametric functions that make a picture (example inside) created?

[Here's] (http://www.wolframalpha.com/input/?i=sergey+brin+curve) an example of what I'm talking about. The equation might take a second to load. How are these generated, computer algorithms? I ...
4
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0answers
96 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?
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1answer
33 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
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1answer
45 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
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1answer
30 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
47 views

Is there an analitical solution for such ODE $$ \frac{d y(x)}{dx}=\frac{a*y(x)^3+b}{c* y(x)^3+ d} $$

I have an ODE $$ \frac{d y(x)}{dx}=\frac{a*y(x)^3+b}{c* y(x)^3+ d} $$, $$a,b,c,d - const$$ And I would love to solve it analitically. I tred maple 15 and 17 and got $$ y \left( x \right) =1/2\,{ ...
0
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1answer
33 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 ...
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3answers
62 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
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3answers
100 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
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1answer
42 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
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1answer
50 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, ...
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2answers
100 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
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2answers
100 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 ...
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3answers
79 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 $2x$. ...
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2answers
89 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
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1answer
218 views

Wolfram Mathematica - Newton Backward Interpolation?

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 + ...
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1answer
72 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) ...
2
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0answers
323 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 ...
0
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2answers
782 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 ...
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1answer
56 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 ...
3
votes
1answer
745 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
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1answer
62 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
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0answers
35 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
51 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
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2answers
99 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) ...
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1answer
320 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
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2answers
127 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
85 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
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0answers
46 views

How to work with the inverse of finite difference on WolframAlpha?

Im taking a course of Discrete Math, we are working with "finite calculus". In Wolfram the discrete derivative is for example the differencedelta(2^x,x) function, ...
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1answer
604 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 ...
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2answers
118 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.
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1answer
176 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: ...
3
votes
1answer
121 views

What's wrong with Wolfram Alpha (or me)? Integral involving exp(-t)

The integral in question $\int e^{-t}\cdot (1+e^{-t})^{-2}dt$ can be solved with an easy $u$-substitution. I'm getting $(1+e^{-t})^{-1}$ which I can verify is correct by derivation. I'm rusty though ...
3
votes
2answers
110 views

Wolfram double solution to $\int{x \cdot \sin^2(x) dx}$

I calculated this integral : $$\int{x \cdot \sin^2(x) dx}$$ By parts, knowing that $\int{\sin^2(x) dx} = \frac{1}{2} \cdot x - \frac{1}{4} \cdot \sin(2x) +c$. So I can consider $\sin^2(x)$ a ...
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4answers
238 views

Why does Wolfram Alpha say that $\sqrt{1}=-1$? [duplicate]

Why does Wolfram Alpha say that $\sqrt{1}=-1$? Is this a mistake or what? Can anyone help? Thanks in advance.
2
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1answer
313 views

Input integral derivative in Wolfram Alpha

How to input $\frac{d}{dx}(\int_0^x \sqrt{t^2-t+1} \,dt)$ in Wolfram Alpha? If i change $dt$ by $dx$ it works, but the output is $\sqrt{t^2-t+1}$, there is no substitution for "$t$" there, if i am ...
0
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1answer
188 views

Input expression with summations in Wolfram Alpha

Wolfram understand this expression , but i need to do the limit when n tends to infinity of that expression . As you can see in the wolfram web itself, in the last link it fails to understand the ...
0
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1answer
112 views

Large system of equations using wolfram alpha.

I'm trying to use Wolfram Alpha to solve a very large system of equations- Variables A through P with a Z. It has 40 equations, so it won't let me use the regular type in the first bar. I tried using ...