# factorising trinomials

Factorising
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Slide 1: Woordweb
WiskundeMiddelbare schoolvwoLeerjaar 2

In deze les zitten 17 slides, met interactieve quizzen en tekstslides.

Lesduur is: 45 min

## Onderdelen in deze les

Factorising

#### Slide 1 -Woordweb

Today we will learn...
How to factorise a trinomial

a + b

a x b
4x + 8 = 4 (x+2)
3x + 5

3a + 4b + 2c
Sum
product
factorisation
binomial
trinomial

#### Slide 3 -Sleepvraag

which two numbers have a product of 20 and a sum of 9?
A
10 and 2
B
3 and 6
C
4 and 5
D
20 and 9

#### Slide 4 -Quizvraag

Which two numbers have a product of 20 and a sum of 21?
A
10 and 2
B
20 and 1
C
4 and 5
D
20 and 21

#### Slide 5 -Quizvraag

Which two numbers have a product of 20 and a sum of -12?
A
10 and -2
B
10 and 2
C
-10 and -2
D
-10 and 2

#### Slide 6 -Quizvraag

Factorising trinomials
• Factorising means to write as a product.
• For trinomials, we use brackets to do this.
• Factorising is the opposite of multiplying out the brackets.

#### Slide 7 -Tekstslide

Removing double brackets

#### Slide 8 -Tekstslide

Factorising trinomials
What do you notice?

#### Slide 9 -Tekstslide

Factorising trinomials
If a trinomial is of the form
(so 1 in front of x-squared, a number in front of x and a single number)
then you can factorise the formula with double brackets

For the numbers on the dots you should find two numbers so that:
.... + .... = b                  the sum of the two numbers in the number in front of x
.... x .... = c                   the product of the two numbers is the single number
y=x2+bx+c
y=(x+...)(x+...)

#### Slide 10 -Tekstslide

Factorising trinomials
Factorise
Make a multiplication table.

We need two numbers on the dots
... + ... = 8 (the sum is 8)
... x ... = 12 (the product is 12)
which two numbers have a sum of 8 and a product of 12?
y=x2+8x+12

#### Slide 11 -Tekstslide

Factorising trinomials
Factorise
Make a multiplication table.

We need two numbers on the dots
2 + 6 = 8
2 x 6 = 12
So the factorised formula is
y=x2+8x+12
y=(x+2)(x+6)

#### Slide 12 -Tekstslide

Try it yourself!
Copy and make this exercise in your Notebook!

Factorise
Make a multiplication table.

We need two numbers on the dots
... + ... = ...
... x ... = ...
So the factorised formula is
y=x2+3x18

#### Slide 13 -Tekstslide

SOLUTION:
Compare with your own work and

Factorise
Make a multiplication table.

We need two numbers on the dots
6 + -3 = 3
6 x -3 = 18
So the factorised formula is
y=x2+3x18
y=(x3)(x+6)

let's practice!