# Tagged Questions

Use this tag when you want to determine the thinking that is needed to solve a certain type of problem, as opposed to looking for a specific answer to a question.

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### Two people running up and down escalators

Couldn't really figure out a good title for this post, I am sorry. But here's the problem: PREMISE: Two people, A and B, are running, with speed u, up and down separate escalators with length L. ...
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### Divide a 2D polygon with N vertices into triangles draw in a 3D space

I'm developing a C++ software and I have a problem with a polygon with N vertices. I have a set of N vertices unordered. This vertices describe an polygon. I'm developing a planetarium and I want ...
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### How many different ways can you order a binary code (only 1s and 0s) if there is 5 of one and 6 of the other?

If you have 6 0's and 5 1's, like in binary, how many different ways can you order them? Also, there is a popup saying that the question appears subjective. Is it?
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### How can the policeman catch the gangster?

I try to solve the following problem (Moscow Mathematical Olympiad, 1978) There is a town with six streets: four sides of a square and two its middle lines. Policeman tries to catch a gangster. If ...
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### Given $f(x)=x^2-4x+3$, find the points on the curve $y=f(x)$ where the tangent to the curve passes through -6.

Given $f(x)=x^2-4x+3$, find the points on the curve $y=f(x)$ where the tangent to the curve passes through $(0,-6)$. State the equations of the tangents at these points. Hi everyone, I tried to find ...
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### Sum of correlated random variables and the Law of Large Numbers?

Suppose I have a random variable $X$ which can take values on the set $\mathcal{X}=\{1,2,\dots,m\}$ and $X$ is drawn according to the given probability mass function $\mathbf{p}=\{p_1,p_2,\dots,p_m\}$...
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### How to debug math?

May seem strange as I'm good in programming, but I just started diving into math. ATM I'm learning combinatorics at Khan Academy, and here's an example of a question that I struggled with (that's not ...
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### Three screw problem

There are three identical screws with diffrent amounts of nuts and disks on them. Here is the problem picture: How do you calculate the weight of a screw, the nuts and the disks?
### How does one get $p=2$ from a condition that there be non-trivial linear transformations of every dimension that to any power are $p$-norm-preserving?
Verifying that (p=2) satisfies \forall n\in\mathbb{Z}^+.\exists A\in(\mathbb{R}^{n\times n}\setminus\{I_n\}).\forall k\in\mathbb{R}.\forall v\in\mathbb{R}^{n}.\left\|A^kv\right\|_p\!\!=\left\|v\...