Explaining, convincing and proving

  • Always Two
    problem
    Favourite

    Always Two

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    Find all the triples of numbers a, b, c such that each one of them plus the product of the other two is always 2.

  • Trapezium made of wooden tangram pieces, including a square and a parallelogram.
    problem
    Favourite

    Quad in Quad

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    Join the midpoints of a quadrilateral to get a new quadrilateral. What is special about it?

  • Iff
    problem
    Favourite

    Iff

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    Take a triangular number, multiply it by 8 and add 1. What is special about your answer? Can you prove it?

  • Negative 3 to the power of negative 3.
    problem
    Favourite

    Negative Powers

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    What does this number mean? Which order of 1, 2, 3 and 4 makes the highest value? Which makes the lowest?

  • Back fitter
    problem
    Favourite

    Back Fitter

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    10 graphs of experimental data are given. Can you use a spreadsheet to find algebraic graphs which match them closely, and thus discover the formulae most likely to govern the underlying processes?

  • Calculating with cosines
    problem

    Calculating With Cosines

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    If I tell you two sides of a right-angled triangle, you can easily work out the third. But what if the angle between the two sides is not a right angle?

  • Kite in a Square
    problem
    Favourite

    Kite in a Square

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    Can you make sense of the three methods to work out what fraction of the total area is shaded?

  • Curve fitter
    problem
    Favourite

    Curve Fitter

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    This problem challenges you to find cubic equations which satisfy different conditions.

  • Always Perfect
    problem
    Favourite

    Always Perfect

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    Show that if you add 1 to the product of four consecutive numbers the answer is ALWAYS a perfect square.

  • Impossible sums
    problem

    Impossible Sums

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    Which numbers cannot be written as the sum of two or more consecutive numbers?