1. Factorising a Quadratic
a, b, c, method
If a quadratic function factorises,
we can ALWAYS use the same steps to factorise it
Step 1 : identify a , b, c?
- Standard form
a = +1
b = +5
c = +6
31-Dec-18
Created by Mr. Lafferty Maths Dept.

2. Factorising a Quadratic
b = +5
c = +6
Factorising a Quadratic
a, b, c, method
If a quadratic function factorises,
we can ALWAYS use the same steps to factorise it
Step 2 :
Find 2 numbers that
multiply ac = 6
add to give b = 5
+3 and +2
Step 3 :
Rewrite the middle term
using the 2 numbers
31-Dec-18
Created by Mr. Lafferty Maths Dept.

3. Factorising a Quadratic
Check !
ALWAYS left with the same brackets
a = +1
b = +5
c = +6
Factorising a Quadratic
a, b, c, method
Step 4 :
Factorise
1st and 2nd terms
Step 5 :
Factorise
3rd and 4th terms
Step 6 :
Take out common factor
in brackets
31-Dec-18
Created by Mr. Lafferty Maths Dept.

4. Factorising a Quadratic
a, b, c, method
Check !
ALWAYS left with the same brackets
Factorising a Quadratic
The 6 steps of the a,b,c method of factorising
1. Identify a, b, c
2. Find two numbers such that they
multiply to give ac and add to give b
3. Rewrite middle term in terms of the
two numbers in step 2.
4. Factorise 1st and 2nd terms
5. Factorise 3rd and 4th terms
6. Take out common factor ( the brackets)
31-Dec-18
Created by Mr. Lafferty Maths Dept.

5. Factorising a Quadratic
a, b, c, method
Step 1 : identify a , b, c?
a = +2
b = +9
c = +4
31-Dec-18
Created by Mr. Lafferty Maths Dept.

6. Factorising a Quadratic
b = +9
c = +4
Factorising a Quadratic
a, b, c, method
If a quadratic function factorises,
we can ALWAYS use the same steps to factorise it
Step 2 :
Find 2 numbers that
multiply ac = 8
add to give b = 9
+8 and +1
Step 3 :
Rewrite the middle term
using the 2 numbers
31-Dec-18
Created by Mr. Lafferty Maths Dept.

7. Factorising a Quadratic
Check !
ALWAYS left with the same brackets
a = +2
b = +9
c = +4
Factorising a Quadratic
a, b, c, method
Step 4 :
Factorise
1st and 2nd terms
Step 5 :
Factorise
3rd and 4th terms
Step 6 :
Take out common factor
in brackets
31-Dec-18
Created by Mr. Lafferty Maths Dept.