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For mathematical questions related to the usage of WolframAlpha.

637 questions

0votes0answers18views

How do I plot a gigantic function easily on WA?

I need to graph a gigantic function on WA, that has other functions inside it and some constants with preassigned values that come up a lot! For example: W = QbBesselK...., in which Q is an equation ... user avatar Laura Martins

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5votes1answer85views

How does Wolfram Alpha find polynomial equation of given roots?

I am experimenting with a method which will converge hopefully to a real number, for which I suspect, that it is the root of a polynomial equation. How does Wolfram Alpha find its guess? How does WA ... user avatar mathoverflowUser

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0votes0answers57views

Proof of equality given by wolfram alpha

By 'playing' with wolfram alpha and entering this sum $$\sum_{n=0}^{+\infty}(-1)^n\left(\frac{1}{1+nx}+\frac{1}{x-1+nx}\right)$$ I found this alternative form that interest me: (since I don't know the ... user avatar As soon as possible

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-1votes2answers36views

Solve basic system of equations with two unknowns. Why solution doesn't exists? [closed]

The following equation has no solution, but I'm not sure why exactly: $7 = 3x_1 + 5x_2 \\ 13 = (1 - x_1)3 + (1 - x_2)5 + 21$ Code for Wolfram Alpha ... user avatar baxx

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0votes1answer48views

Maximum of $\frac{Bx}{x^3 + Rx + P}$

I submitted this function to Wolfram Alpha and similar tools, but none can find for me the symbolic expression for maximum value, unless I give specific values to each parameter: $$\frac{Bx}{x^3 + Rx +... user avatar jumpjack

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0votes1answer55views

Numerical error in wolfram

In Wolfram Alpha, we see that $$\sum_{n=0}^\infty\frac{e^{-\pi^2n(n+1)}}{2n+1}=1$$ This is equivalent to $$\sum_{n=1}^\infty\frac{e^{-\pi^2n(n+1)}}{2n+1}=0$$ However, the last sum is impossible since ... user avatar sinbadh

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1vote0answers36views

Why is there a term $3.70074\times 10^{-17}x^2$ in this solution?

I was using WolframAlpha to find a polynomial of degree up to $2$ that best fits the points $(-1,2),(0,0),(1,-2),(2,-4)$. The answer I was expecting is $$0x^2-2x+0.$$ However, here is what ... user avatar Zuriel

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2votes1answer54views

How to compute $ \sum_{x=y}^\infty \binom{x}{y}((1-p)(1-q))^x$?

Question How do I compute $ \sum_{x=y}^\infty \binom{x}{y} ((1-p)(1-q))^x$? $x,y$ are integers and $p, q \in (0,1)$ Attempt I'm trying to compute this sum to find the mixture of a geometric and ... user avatar iggykimi

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1vote1answer21views

Polar plot is different from rectangular plot

Here is a polar equation $r = \tan(\theta) $. I converted it into the rectangular form. This would be $$ \sqrt{x^2 + y^2} = \frac{y}{x} $$ When I plot both in ... user avatar user9026

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Nonsense matrix multiplication defaults in WolframAlpha

I just realized WolframAlpha arbitrarily decides which way to multiply matrices based on seemingly irrelevant stuff, and I'd like to understand whether the issue is with my knowledge of what's ... user avatar Rusca8

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Find the maximum value of:$3\sqrt[3]{\dfrac{c^2-3a^2}{6}}-2\sqrt{\dfrac{a^2+b^2+c^2-ab-bc-ca}{3}}$

Let $a,b,c \in R$, find the maximum value of:$$3\sqrt[3]{\dfrac{c^2-3a^2}{6}}-2\sqrt{\dfrac{a^2+b^2+c^2-ab-bc-ca}{3}}$$ I have the solution: $$5a^2+2b^2+c^2-2(ab+bc+ca)=5(a-\frac{b+c}{5})^2+\frac{1}{5}... user avatar trungbk

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3votes1answer46views

Restricting Domain in Wolfram Alpha for Nested Quantifiers

Is there a way to restrict the domain to all positive integers when you're using Resolve[] on nested quantifiers in Wolfram Alpha? If so, how? If not but there is ... user avatar daniell_regent

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4votes2answers290views

Wolfram Alpha wrong Integral

I want to evaluate the following integral: $$\int_{-\infty}^0\frac{R}{\sqrt{x^2+R^2}^3}\mathrm{d}x$$ If I do it with the substitution $x=R\tan(\varphi)$ I get: $$\int_{-\infty}^0\frac{R}{\sqrt{x^2+R^2}... user avatar Silas

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Wolfram alpha gives two different answers for $\int^{\infty}_{-\infty} x \frac{1}{\pi} e^{-(\ln(x) - 0.3)^2} | \frac{1}{x}|dx$

So, I'm trying to calculate $$\int^{\infty}_{-\infty} x \frac{1}{\pi} e^{-(\ln(x) - 0.3)^2} \left| \frac{1}{x}\right|dx$$ When I input that into WA, it loads for a bit, then shows this result: Just ... user avatar Rararat

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Matrix Power and Power Incorrect in Wolfram Alpha? [closed]

When computing the matrix \begin{bmatrix}1 & -\sqrt{3} \\ \sqrt{3} & 1\end{bmatrix} times its inverse, Wolfram Alpha produces this incorrect result. The same result happens when Power is ... user avatar Samuel D

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