How To Factorise Quadratics Faster Than Eating Biscuits

How to Factorise Quadratics Faster Than Eating BiscuitsPosted on April 13, 2023 by ZanSo, you’ve discovered the joy of quadratics – or not – and you’ve realised they are a popular topic in the GCSE Maths Exam.

In one of my very first posts, I stated how critical times tables are to improve your maths.

If you want to be good at factorising you will need to be super speedy with your times tables, at least up to the 12 times table.

The more you know, the easier factorising becomes.

There are two types of quadratics you will need to factorise.

The first type are the ones that start with x2 i.e. there is always only 1 x2.

The second type is where you can have any number before the x2, and this gets tricky.

That number is called the coefficient of x2.

Let’s start with the the first type.

Here’s an example:

x2 + 5x + 6.

Here’s the way I do it:

Draw your brackets, with an x in each – that sorts out the x2.

(x )(x )

Now, the second and third part of the equation are both positive, so everything in the brackets should be positive.

(x + )(x + )

To choose the correct numbers that will complete the bracket, we need two factors of 6, that add up to make 5.

Easy – 3 x 2 =6, and 3+2 = 5

(x + 3)(x + 2)

If you multiply that out (always check your answers, especially in the exam where stress makes you do crazy things)

x2 + 3x + 2x + 6 which gives our original equation: x2 + 5x + 6

To summarise the method:

Write out the xs and work out if you need negative or positive signs in the bracketsList the factors of the last part of the equation and find the ones that add up to make the 2nd partFinish the brackets and check your answers

So why did we not use the factors 6 and 1?

(Read the rest at www.gcsemathshacks.com)