Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [problem-solving]

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.

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.

4495 questions
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Terence Tao's problem solution

Suppose you are trying to get from one end $A$ of a terminal to the other end $B$. (For simplicity, assume the terminal is a one-dimensional line segment.) Some portions of the terminal have moving walkways (in both directions); other portions do…
UserX
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Mathematical Rube Goldberg problem

Is there a book or website that has mathematical rube goldberg-style puzzles? In other words, puzzles that require you to compute something, then compute something based on that, and then iterate for a large number of steps. These puzzles should…
user107952
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How to Think Better

I just took a quiz and am dumbfounded by my lack of insight. Consider what kind of idiot I'd have to be to do the following: Point A = (8,-15) and point B = (-8,15). P is the locus of points (x,y) such that AP • BP = 0. Describe the elements in…
Nursultan Tulyakbay
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Problem Solving Question (Riddle)

The problem I need to solve is written as the following: Four people want to cross a bridge on a very dark night. They all begin on the same side and want to do the crossing as quickly as possible. A maximum of two persons can cross the bridge at…
Math Student
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simple math question from civil service exam

The weight per foot of a length of square bar 4" x 4" in cross section as compared with one 2" x 2" in cross section, is ______ as much. A. Twice B. 2 1/2 times C. 3 times D. 4 times This question exactly as writtin appears in NY states civil…
MrPizzaFace
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How can I solve this puzzle using equations?

There's a hall with 100 seats. I want to fill up these seats with men, women and children; they're going to purchase seat positions. The cost per seat for men is 5 USD, women 1 USD, and children 0.05 USD. I want to get 100 USD from selling all 100…
Alaa Ali
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How to solve for $x$ in the function $y=x\ln(x)$?

I have $y=x\ln(x)$ and I need to solve for x. How am I supposed to do that? Because I get $y=x\ln(x)$ $y=\ln(x^x)$ $e^y=x^x$ and I am stack here... Can somebody help me? EDIT In my case the result of y is always a real positive number (y>=1).…
K. Stasko
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Elements and Unions

Need help solving this problem step by step!
user160979
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Problem of the month. Thinking problem?

Cherise scored 85 on her last math exam of 100 questions. Her teacher has an unusual way of scoring this test. He calculated her score by subtracting 2 times the number of wrong answers from the number of correct answers. If Cherise answered all…
user136159
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Solving an equation

Integrating gives $$\ln\frac{250-X}{40-X} = 210kt+c_1\qquad\text{or}\qquad \frac{250-X}{40-X}=c_2e^{210kt}.\tag{10}$$ When $t=0, X=0,$ so it follows at this point that $c_2 =\frac{25}{4}$. Using $X=30g$ at $t=10$, we find…
Javittoxs
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Infinetly many primes of form $4k+3$

Prove that there are infinitely many primes of the form $4k + 3$ (where $k$ is an integer). Note that it is a special case of "Theorem 6 (Dirichlet). Let a and b be positive coprime integers. Then the sequence $b$, $b + a$, $b + 2a$, $b + 3a$, $b +…
John
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Finding F(x) given any reals x and y

I have a problem and I think I know how to solve it so here it is: Determine $F(x)$ if, for all real $x$ and $y$, $F(x)F(y)-F(xy) = x+y$. I tried a couple of cases and these were my results: When $x=0$ and $y=0$ then $F(0) = 1$. When $y=0$ and $x$…
InsigMath
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How many ordered triples $(x,y,z)$ of positive integers satisfy $xyz=4000$

How would I find this out? Is there an equation or summation?
Ella
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Right angle triangle simple problem

The number of degrees in one acute angle of a right-angled triangle is equal to the number of grades in the other; express both the angles in degrees. So I have found the following answers : 810/17=47,05... degrees and 810/17=47,05... grades which…
user108343
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A confusion(possible book mistake) about one of the proofs in Spivak's Calculus?

In Chapter 5 - Function Limits, there is a proof that: if $|x - x_0| < 1; |x - x_0| < \frac{\epsilon}{2(|y_0| + 1)}; |y - y_0| < \frac{\epsilon}{2(|x_0| + 1)}$ then $|xy = x_0y_0| < \epsilon$ The solution offered is: Since $|x - x_0| < 1 => |x| < 1…
darkradeon
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