For questions related to usage of Wolfram Alpha.

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1answer
62 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
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1answer
1k 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
78 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 - ...
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0answers
42 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
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1answer
58 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
110 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
463 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 ...
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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
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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 ...
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0answers
47 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
896 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
159 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
226 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
130 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
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2answers
119 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
254 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
404 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 ...
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1answer
275 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 ...
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1answer
127 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 ...
2
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1answer
547 views

How to compute the modular multiplicative inverse on WolframAlpha?

$e = 17$ $\varphi(3233) = (61 - 1)(53 - 1) = 3120$ Compute d, the modular multiplicative inverse of e (mod φ(n)) yielding d = 2753. ...
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2answers
88 views

derivative, the way to show in a graph

http://www.wolframalpha.com/input/?i=derivative+x%5E2%2C+x%5E2 Just reminding myself some math.. Is it ok to show the derivative in such a way like was shown in the link above for $x^2$ function? A ...
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1answer
78 views

Nonlinear regression analysis of a vector

I'm trying to get a nonlinear fit of a vector in Matlab with no success. Let's assume that I have a vector called data: data = [1,30,250,55,22,76] which can be ...
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1answer
1k views

How to input this into Wolfram Alpha?

I wish to simplify a sum by doing "simplify sum_{a=0}^L f(a)" where $f(a)$ is just some arbitrary expression, but I want to only do the sum when some condition is met. Using the Iverson brackets, I ...
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1answer
50 views

Using Wolfram to convert a value chart into graph

Is it possible to use Wolfram Alpha to make something like this into a graph and have it display the proper function? In that case, how would I syntactically write it in Wolfram?
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1answer
630 views

How do I input these interval equation in to wolfram to show me the solution

How do I enter these equation into wolfram to show me the interval type equation which gives the solution as exact values.. Question 1 : $2\tan x\cos x = \tan x$ where $0\leq x< 2\pi$ Question 2: ...
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2answers
121 views

How do I enter the equation $y=\sin\frac{2\pi }{3}x$ into Wolfram Alpha? [closed]

How do I enter this equation into wolfram? Any help would be much appreciated. I'm not sure how to do the brackets. $$y=\sin\frac{2\pi }{3}x$$
2
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3answers
193 views

arithmetic operations on alephs in WolframAlpha

Can someone please enlighten me if or how both of these facts can be true? I entered $\aleph_0-\aleph_0$ into WolframAlpha, which gave the result as undefined. But it also plotted the result on a ...
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1answer
104 views

Am I right or is Wolfram right?

Let ${a_n}$ be a sequence whose corresponding power series $A(x)=\sum_{i\geq 0}a_ix^i$ satisfies $$A(x)=\frac{6-x+5x^2}{1-3x^2-2x^3}$$ Determine a recurrence relation that ${a_n}$ satisfies. I ...
4
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1answer
69 views

Polar coordinations - problem with r and $\theta$

let's take a look on Archimedean spiral. the polar equation is $r = \theta$. click here to look. but $\tan (\theta) = y/x$ and $r = \sqrt{x^2+y^2}$, so $r = \theta \rightarrow \tan(\sqrt{x^2+y^2}) ...
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2answers
95 views

Series expansion with remaining $log n$

I'm studying the asymptotic behavior $(n \rightarrow \infty)$ of the following formula, where $k$ is a given constant. $$ \frac{1}{n^{k(k+1)/(2n)}(2kn−k(1+k) \ln n)^2}$$ I'm trying to do a series ...
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1answer
529 views

Mathematica vs Wolfram Alpha integration results

When I insert the following integration command in wolframalpha: ...
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0answers
67 views

Strange results for solving boundary angle of full reflection

I was trying to solve the following group of equations for $\alpha$ using Wolfram|Alpha: $$\frac{v_2\cdot\sin(\alpha)}{v_1} = 1 \\ v_1 > 0 \\ v_2 > 0$$ I expected something like $\alpha = ...
5
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1answer
151 views

Why doesn't $ \lim_{(x,y)\rightarrow(0,0)} xy\sin(\frac{1}{xy}) $ exist?

I've tried to get the following limit: $$ \lim_{(x,y)\rightarrow(0,0)} xy\sin\left(\frac{1}{xy}\right) $$ wolfram claims it doesn't exist. How to show that? Why can't I take $z=xy$ and receive a ...
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1answer
263 views

Numerical values of the Jacobi elliptic function sn: Wolfram Alpha vs. Maple vs. C++?

I have a problem to check the validity of an algorithm I've implemented in C++ to compute the Jacobi elliptic function $\mathrm{sn}(u, k)$ (inspired and improved from Numerical Recipes 3rd edition). I ...
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1answer
156 views

Is Wolfram Alpha correct?

Given the attempted derivative at http://www.wolframalpha.com/input/?i=d%28a%28x%29+choose+b%28x%29%29%2Fdx, I believe the result from Wolfram Alpha is off by a factor of 2 or, at least I get a result ...
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2answers
417 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 ...
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1answer
416 views

What does a dot after a number mean?

So I'm making some calculations for numerical analysis and the output I get in Wolfram or Mathematica for input like: ...
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4answers
592 views

The last few digits of $0^0$ are $\ldots0000000001$ (according to WolframAlpha).

Can anybody explain how this comes about?
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4answers
1k views

Wolframalpha - how to get value of function in a specific point?

For example , given this function - $f(x) = x^3-x^2-x-1$ and I want to check it in the point $x=1.6$. What should I have to write in the command line of wolframalpha in order to get it ?
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3answers
109 views

Generating function with quadratic coefficients.

$h_k=2k^2+2k+1$. I need the generating function $$G(x)=h_0+h_1x+\dots+h_kx^k+\dots$$ I do not have to simplify this, yet I'd really like to know how Wolfram computed this sum as ...
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1answer
367 views

How to calculate vector * matrix-inversed in Wolfram Alpha?

I am trying to calculate the product of a vector and an inversed matrix in wolfram alpha: $\begin{bmatrix}1 & 2 & 3\end{bmatrix}$ * $\begin{bmatrix} -0.5 & 0 & 0 \\ 3 & 1 & 0 ...
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1answer
329 views

Getting weird integral evaluation from Wolfram Alpha

Check this out. I hand-evaluated this integral and my pretty sure the answer is zero, but Wolfram returns the value $4i\pi$ instead.
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1answer
43 views

Permutations - bug in Wolfram Alpha?

I've got question whether Wolfram Alpha has bug in showing permutations. Check permutation rules, list, and two-line notation in this permutation. I'd expect same result as was on Wolfram Alpha blog ...
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2answers
573 views

Wolframalpha step-by-step of $\int\frac{\cos(x)}{\sqrt{2+\cos(2x)}}dx$

I wonder, where the minus sign goes after the first $u$-substitution of integral $\displaystyle\int\frac{\cos(x)}{\sqrt{2+\cos(2x)}}dx$?
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4answers
457 views

Why WolframAlpha Result is Different?

http://www.wolframalpha.com/input/?i=x%3D10%5E-15%3B+%28e%5Ex-1%29%2Fx When i click Approximate Form in result, the result is: ...
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5answers
809 views

Find the second derivative of $e^{x^{3}}+7x$

$$e^{x^{3}}+7x$$ Here is what I have tried so far, $$y'=(e^{x^{3}})'+(7x)'$$ $$y'=3e^{x^{2}}e^x+7$$ $$y'=3e^{x^{3}+x}+7$$ I am supposed to find the second derivative but I believe I have already made ...
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2answers
3k views

How to enter subscript characters in WolframAlpha? [closed]

I'm trying to enter equations like this in WolframAlpha. How do I format this?
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1answer
144 views

Equation with 2 variables tricky problem

So let's say I have some random equation $6yx^3 - 3yx + 5 = 0$, but could be anything. How would I go about finding a value for $y$, that makes it so that this equation only holds true if $x$ is ...
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4answers
1k views

Wrong Wolfram|Alpha limit?

I have this function: $$ f(x,y) = \frac {xy}{|x|+|y|} $$ And I want to evaluate it's limit when $$ (x,y) \to (0,0)$$ My guess is that it tends to zero. So, by definition, if: $$ \forall \varepsilon ...
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3answers
1k 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?