Recent content by dpesios

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    Isosceles hyperbola locus problem

    So, the answer is that there is no locus or the locus contains just one point and the contact points with the curve are at infinity as I initially proposed (?). If it is so, I must play lottery. :rolleyes: Thank you for your time.
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    Isosceles hyperbola locus problem

    I see your point but there is always a but ... :frown: No matter how hard I try, I cannot figure out an equation by eliminating x',x'',y' and y''. Maybe there is another way of solving the problem. I don't know. What do you think ?
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    Isosceles hyperbola locus problem

    Yes, I do mean rectangular hyperbola. When it comes to geometry it is all Greek to me ... :confused: I'm not sure whether we should say "conducted tangent from a given point" or "subtended tangent". As far as I understand two tangent lines start from a point on the locus and touch the...
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    Isosceles hyperbola locus problem

    Hello all, I would like beforehand to inform you that the translation of the following geometric problem is not very good and consequently you will have to use your mathematical intuition just a little bit. I encountered it while giving admission exams in a Mathematics department to pursue a...
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    A set A of n elements has n(n-1)/2 subsets of 2 elements

    if we add an element to the set which previously had k elements (that is now has k+1 elements) the new subsets that include the new element will be : (k+1)k/2 - k(k-1)/2 = k So, how can we argue that this will solve the problem ?
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    A set A of n elements has n(n-1)/2 subsets of 2 elements

    I would very much like some help to the following problem. Homework Statement Using mathematical induction, prove that a finite set A of n elements has n(n-1)/2 subsets of two elements. The Attempt at a Solution * Base step n=2: 2(2-1)/2= 1 subset of two elements. * Inductive step: assuming...
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    How can I prove that n^3 + (n+1)^3 + (n+2)^3 is a multiple of 9?

    Thanks for the answer, Okay, here is my solution. I thought that at the problem defintion "is divisible by" and "is a multiple of" makes a huge difference. The base case is obvious. Let that the statement holds for n=k, that is, k^3+(k+1)^3+(k+2)^3 is a multiple of 9. We will then show that...
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    How can I prove that n^3 + (n+1)^3 + (n+2)^3 is a multiple of 9?

    Hello everybody, I am doing my reading lately to prepare for some exams to join a mathematics department. And I would very much like, if anyone could help, the solution (or a hint) to the following induction proof. " Show that n^3 + (n+1)^3 + (n+2)^3 is a multiple of 9 " :smile: I...
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    If F'(x) is bounded so is F(x)

    Thanks for the reply, Indeed the "vice-versa" does not hold for every function F(x) as it has also been discussed https://www.physicsforums.com/showthread.php?t=515616&highlight=bounded+function+derivative". How can we argue that F(x) is bounded ? :confused: By intuition the statement is...
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    If F'(x) is bounded so is F(x)

    Hello everybody, A few years ago i tried to join a mathematics department and in the relevant exams i came up against the following problem. I apologise beforehand if the statement of the problem is a little bit ambiguous because i do not remember it exactly. However, I am sure you will get...
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