Inequalities

  • Eyes Down
    problem
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    Eyes Down

    Age
    16 to 18
    Challenge level
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    The symbol [ ] means 'the integer part of'. Can the numbers [2x]; 2[x]; [x + 1/2] + [x - 1/2] ever be equal? Can they ever take three different values?
  • In Between
    problem
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    In Between

    Age
    16 to 18
    Challenge level
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    Can you find the solution to this algebraic inequality?
  • Random inequalities
    problem
    Favourite

    Random Inequalities

    Age
    16 to 18
    Challenge level
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    Can you build a distribution with the maximum theoretical spread?
  • Two Cubes
    problem

    Two Cubes

    Age
    14 to 16
    Challenge level
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    Two cubes, each with integral side lengths, have a combined volume equal to the total of the lengths of their edges. How big are the cubes? [If you find a result by 'trial and error' you'll need to prove you have found all possible solutions.]
  • Code to Zero
    problem

    Code to Zero

    Age
    16 to 18
    Challenge level
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    Find all 3 digit numbers such that by adding the first digit, the square of the second and the cube of the third you get the original number, for example 1 + 3^2 + 5^3 = 135.
  • Without Calculus
    problem

    Without Calculus

    Age
    16 to 18
    Challenge level
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    Given that u>0 and v>0 find the smallest possible value of 1/u + 1/v given that u + v = 5 by different methods.
  • Reciprocals
    problem

    Reciprocals

    Age
    16 to 18
    Challenge level
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    Prove that the product of the sum of n positive numbers with the sum of their reciprocals is not less than n^2.
  • Diverging
    problem

    Diverging

    Age
    16 to 18
    Challenge level
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    Show that for natural numbers x and y if x/y > 1 then x/y>(x+1)/(y+1}>1. Hence prove that the product for i=1 to n of [(2i)/(2i-1)] tends to infinity as n tends to infinity.
  • Climbing
    problem

    Climbing

    Age
    16 to 18
    Challenge level
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    Sketch the graphs of y = sin x and y = tan x and some straight lines. Prove some inequalities.
  • Classical Means
    problem

    Classical Means

    Age
    16 to 18
    Challenge level
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    Use the diagram to investigate the classical Pythagorean means.