# Factorising Quadratics

Highest Common Factor Method

- Created by: Madiha
- Created on: 26-09-11 13:22

First 275 words of the document:

Factorising Quadratics(where last sign is a plus) Example

2

1) 4x 12x+9

Times, first number by last number 4x9= 36

Find all the pairs of factors of 36 until you find the pair that add up to

the middle number12

1x36

6x6 (6+6=12)

Prepare two brackets

( )( )

2) Compare the first number of the Quadratic equation (4x2 12x+9) with the first

number in the pair of factors (6x6) and find a factor of both numbers

A factor of 4 and 6 is 2 so therefore, 2 will be the first number in the

bracket which means we will put an X next to it

( 2x )( )

3) Compare the last number of the quadratic equation (4x2 12x+9) with the last

number of the pairs of factors (6x6) and find a factor of both numbers

A factor of 9 and 6 is 3, therefore, to complete the bracket we will put

3 next to the 2x

However to determine if the sign is + or , you would have to look at

the first sign in the quadratic equation. In this case, sign

(2x3)( )

4) Finally to finish of you need to times the 2x by ....to get 4x2, therefore the number in

the second bracket will be 2x because 2xX2x is 4x

(2x3)(2x )

To determine the number in the second bracket after the 2x, you will

need to find a number that will times 3 to give you the last number of

the quadratic which is 9. 3x3 is 9 therefore, 3 will be put next to the

2x in the second bracket

(2x3)(2x3)

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