Turning Points

Turning points

  • You can find the turning point of a quadratic graph by writing the function in completed square form
  • Make sure you are confident with completing the square before tackling this page

Golden rule

  • The graph of y=(x-a)^2 + b has a turning point at(a,b)

Problem solved

  • If a question asks you to sketch the graph of a quadratic function you should use algebra to find the turning point and any intercepts with the coordinate axes
    • Complete the square to find the turning point
    • Set x=0 to work out the y-intercept
    • Draw axes with a ruler then a sketch the graph
    • Mark the coordinates of the turning point and the point where the graph crosses the y-axis and label your graph