Year 10 Interactive Maths - Second Edition

Quadratic Equations

Solving Quadratic Equations

We will consider the following methods to solve a quadratic equation:

• Factorising and using the Null Factor Law
• Quadratic formula

The Null Factor Law

From this we can infer that:

If the product of any two numbers is zero, then one or both of the numbers is zero.
That is, if ab = 0, then a = 0 or b = 0 (which includes the possibility that a = b = 0).

This is called the Null Factor Law; and we use it often to solve quadratic equations.

Example 1

Solution:

Key Terms

quadratic equation, Null Factor Law, NFL