How to factorise How to factorise simple quadratic simple quadratic

equations.equations.

You need to factorise the following You need to factorise the following equation to win the pub quiz!equation to win the pub quiz!

2 2 24 0x x

Step 1: List all the factor pairs Step 1: List all the factor pairs of 24of 24

You could use a factor pair diagram to help you.A factor pair diagram being used to find all the factors of 24.

1 2 3 4 6 8 12 24

Factor pairs are:

1 x 24, 2 x 12, 3 x 8, 4 x 6

2 2 24 0x x

Step 2: add the factor pairs Step 2: add the factor pairs together to make the coefficient of together to make the coefficient of

xx2 2 24 0x x Factor

pairs1 x 242 x 123 x 84 x 6

We need to make + 2. We also know that we need a negative number since we have -24.

Looking at the factor pairs, we can see that + 6 – 4 would give us + 2

Step 3: we can now factorise Step 3: we can now factorise since we have all the information since we have all the information

we need.we need.2 2 24 0x x

( 4)( 6) 0x x

However we could check we are However we could check we are correct by expanding the correct by expanding the

brackets.brackets.

In school, you were probably shown the ‘smiley face’ method, given below. However, if you still find this rather confusing, you might consider using the grid method shown on the next page.

( 4)( 6) 0x x 2 26 4 24 which simplifies to 2 24 0x x x x x

The grid method of The grid method of multiplication for (x – 4)(x + 6)multiplication for (x – 4)(x + 6)

x4x

6

2x 4x

6x 24

2 26 4 24 which simplifies to 2 24 0x x x x x