Expanding and factorising quadratics

  • Telescoping Functions
    article

    Telescoping functions

    Take a complicated fraction with the product of five quartics top and bottom and reduce this to a whole number. This is a numerical example involving some clever algebra.
  • 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.
  • Common Divisor
    problem

    Common divisor

    Age
    14 to 16
    Challenge level
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    Find the largest integer which divides every member of the following sequence: 1^5-1, 2^5-2, 3^5-3, ... n^5-n.
  • Novemberish
    problem

    Novemberish

    Age
    14 to 16
    Challenge level
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    a) A four digit number (in base 10) aabb is a perfect square. Discuss ways of systematically finding this number. (b) Prove that 11^{10}-1 is divisible by 100.
  • Fibonacci Factors
    problem

    Fibonacci factors

    Age
    16 to 18
    Challenge level
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    For which values of n is the Fibonacci number fn even? Which Fibonnaci numbers are divisible by 3?
  • Multiplication Magic
    problem

    Multiplication magic

    Age
    14 to 16
    Challenge level
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    Given any 3 digit number you can use the given digits and name another number which is divisible by 37 (e.g. given 628 you say 628371 is divisible by 37 because you know that 6+3 = 2+7 = 8+1 = 9). The question asks you to explain the trick.
  • Never Prime
    problem

    Never prime

    Age
    14 to 16
    Challenge level
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    If a two digit number has its digits reversed and the smaller of the two numbers is subtracted from the larger, prove the difference can never be prime.
  • Spinners
    problem

    Spinners

    Age
    16 to 18
    Challenge level
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    How do scores on dice and factors of polynomials relate to each other?
  • Composite Notions
    problem

    Composite notions

    Age
    14 to 16
    Challenge level
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    A composite number is one that is neither prime nor 1. Show that 10201 is composite in any base.