### Chapter 9 - Quadratics and quadratic equations

This chapter discusses quadratics. It contains the following sections:
- section 9.1 - In this section we introduce
quadratic expressions, quadratic equations, quadratic functions and parabolas.

- section 9.2 - In this section we
explain the “
*completing the square*” method, a versatile method that is the
basis for factoring any quadratic trinomial and solving any quadratic equation.

- section 9.3 - In this section we show how
the completing-the-square method can be used to factor any quadratic trinomial.

- section 9.4 - In this section we show how
to solve quadratic equation by four different methods: