Quadratic Graphs (OCR GCSE Maths): Revision Note

Quadratic Graphs

What are the key features of a quadratic graph?

• The point where the graph turns is called the vertex

  • Positive quadratics have a minimum point

    • The bottom of the u-shape

  • Negative quadratics have a maximum point

    • The top of the n-shape

• Quadratic graphs always have a vertical line of symmetry down the middle

  • The equation of the vertical line of symmetry is  x = k

    • k is the x-coordinate of the minimum or maximum point

• Quadratic graphs do not have to cross the x-axis

  • If they do, two x-intercepts are created, called roots

    • If the curve just touches the x-axis, only 1 root is created

  • Roots are symmetric about the vertical line of symmetry

• Quadratic graphs always have one y-intercept