Factorise Into a Single Bracket

Sometimes the common factor that you need to factorise an expression is not a number, but a letter.

Look for the highest power of each letter that will go into every term of the expression.

This will be your common factor to put outside the bracket.

Have a look at this example to see this in action.

e.g. Factorise 3a³ + 2ab.

There is no number which is a common factor of 2 and 3.

The common letter in both terms is a.

The highest power of a that goes into both terms is 1, so the common factor is a.

This means we need to put a outside of the bracket:

a(__ _ __)

But what goes inside?

We need to divide both terms by a to calculate this. 

3a³ ÷ a = 3a²

2ab ÷ a = 2b

So our final answer is: a(3a² + 2b)

In this activity, we will factorise expressions into a single bracket using letters or numbers as common factors.