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28 votes
4 answers
6k views

Consider a man who travelled exactly 2 km in two hours. Is there a one-hour interval when he traveled exactly 1 km?

Question : Consider a man who travelled exactly 2 km in two hours. Is there a one-hour interval when he traveled exactly 1 km? Can we make a mathematical argument? I have written my attempt in an ...
whoisit's user avatar
  • 3,227
2 votes
1 answer
85 views

Extending baker's percentages to preferment recipes

I'm trying to solve a simple problem I created for myself. I'm no mathematician, so any help is greatly appreciated. Background In baking and "baker's math", the amount of each ingredient is ...
William H's user avatar
0 votes
0 answers
45 views

Where to apply binomial expansion?

I would like to know where I could apply the expression as part of other equation $$\bigg( 1 + \frac{x}{r} \bigg)^r$$ considering $r \in Z$. It means, in what kind of problem I can use this expression....
K Z Nobrega's user avatar
3 votes
2 answers
1k views

Real world example of an equation with no solution? [closed]

I have just started reading basic algebra and I have this curiosity that came up when solving basic linear equations. Some equations have no solutions. Are there any real world example of equations ...
Abhishek Kumar's user avatar
3 votes
2 answers
92 views

Can we find an inverse of a model for deadtime?

This is kind of a real-world question, in that it comes from the work I do, but I'm just pursuing it for my own edification. When a radiation detector detects an event, it is insensitive to further ...
Greg's user avatar
  • 211
11 votes
3 answers
463 views

Roots of a set of nonlinear equations $ax + yz = b_1; ay + xz = b_2; az + xy = b_3$

Let $a$ be a non-negative real number, $b_1, b_2, b_3$ be real numbers, and $x, y, z$ be variables. Is it possible to analytically find the root closest to origin $(0, 0, 0)$ of the set of nonlinear ...
Ahmet Taha KORU's user avatar
1 vote
1 answer
46 views

What method should I use to solve rational equations like this for a different quantity?

With electronics, various characteristics of a device can often be described by solving one equation for different quantities. The problem that I run into a lot with my textbooks is that I can't ...
CKats's user avatar
  • 13
0 votes
0 answers
70 views

Arc length vs Surface of revolution.

I don't understand why these two problems are solved differently here the first one $fig(1)$ and 2nd one $fig(2)$. Why did we take the limit $\displaystyle \lim_{r\to0^+}\int_r^\pi \sqrt{2-2cost}\...
user avatar
0 votes
1 answer
63 views

Why can we apply the surface area of revolution theorem to a spiral?

To find the surface area generated by revolving function f which is smooth on the interval [a,b] and $f(y) \ge0$ around the y-axis we can use the formula $$S=\int_a^b 2\pi rdl =\int_a^b 2\pi f(y)\...
Youssef Mohamed's user avatar
1 vote
1 answer
61 views

Why can we say here that $\Delta x_i=dx$ as $i$ approaches infinity?

In the proof of the arc length formula we assume that an element of the arc length is $$\Delta L_i=\sqrt{(\Delta x_i)^2+(\Delta y_i)^2}=\sqrt{1+\left(\frac{\Delta y_i}{\Delta x_i}\right)^2}\space \...
user avatar
1 vote
1 answer
50 views

Calculus application question

My attempt: Step 1: Find $x$ in terms of $t$. $\frac{dt}{dx} = \frac{1}{-0.15x}$ $t = \frac{1}{-0.15}\ln(x) = x^{-1}(t)$ $x(t) = e^{-0.15t}+c$ However, here is where I am stuck. Without any extra ...
Shooting Stars's user avatar
3 votes
1 answer
67 views

Seemingly conflicting notions of a function

Throughout my mathematical education, I have seen a few, seemingly, different and conflicting notions of what a function is: A function is a a type of mathematical object that maps every element of a ...
user avatar
0 votes
1 answer
319 views

Calculus - Calculate Work done to lift water out of tank

I need help setting up the integral so that I can calculate the work done. I've tried it many times and have referred to Youtube, slader, the textbook, and also this site, but I still don't get how to ...
sam's user avatar
  • 133
0 votes
0 answers
380 views

What are the real life application of absolute function?

The well-known absolute function $|x|$ has many uses in mathematics, physics, etc. I know one of the majority applications of abs function in the alternative current making with diodes. But it is ...
Khosrotash's user avatar
  • 25.2k
0 votes
1 answer
60 views

Interpretation and use of the logarithmic scale for high school students

Often when we discuss on the logarithms in high school we also talk about a scale called logarithmic. In the he logarithmic scale: the distance from $1$ to $2$ is the same as the distance from $2$ to ...
Sebastiano's user avatar
  • 7,814

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