Section 4 - Quadratic Functions

Learning intentions:

In this section we will examine:

    • How to expand and factorise quadratics.
    • Solving quadratic equations by factorising, completing the square and using the general quadratic formula.
    • Using the discriminant to determine the number of solutions for a quadratic equation.
    • Graph quadratic functions in general form, turning point form or factorised form.
    • Solving quadratic inequalities.
    • Solving simultaneous equations involving a quadratic and a linear function.
    • Determining the rule of a quadratic function.
    • Applications and modelling of problems with quadratic functions.

Introduction:

Section 4 introduces quadratic functions. A quadratic function is a polynomial with the highest power (n) being 2. The graph of a quadratic is a parabola. There are three important forms that a quadratic equation can be expressed in:

  • The general form of a quadratic equation is:
    • The turning point form of a quadratic equation (with turning point (h,k)) is:
    • The factorised form of a quartic equation (where the x-intercepts occur at (b,0) and (a,0) is:

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