4C - Solving quadratic equations

Learning intentions:

In this section we will examine:

    • The null factor law and its use in solving simple quadric equations

Solving quadratic equations

The null factor law

The null factor law states:

Using the null factor law to solve quadratic equations

The null factor law can be used to solve simple quadratic equations. To solve quadratic equations, use the following steps:

    1. Get the quadratic equation to equal zero; that is, ax2 + bx + c = 0.
    2. Factorise the quadratic expression.
    3. Use the null factor law to find the solution

4C - VIDEO EXAMPLE 1:

Solve the following equation for x:

Note: The discriminant

(Δ) can be used to determine the number of expected solutions.

4C - VIDEO EXAMPLE 2:

Solve the following equation for x:

4C - VIDEO EXAMPLE 3:

Solve the following equation for x:

Success criteria:

You will be successful if you can:

    1. Apply the null factor law to factorised expressions to solve basic quadratic equations.