# 2TH §11.1 Factorising

What will we do today...
• Questions about the homework? R3 until R9 (skip R6)
• Recap terms and factors
• Recap sum and product
• Recap prime numbers
• We do together: Ch 11: Exercises R1 and R2
• Homework: Ch 11.1 Do Exercises 3, 4, 6, 7, 8
• Exit ticket
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Slide 1: Tekstslide
WiskundeMiddelbare schoolhavoLeerjaar 2

In deze les zitten 15 slides, met interactieve quizzen en tekstslides.

Lesduur is: 50 min

## Onderdelen in deze les

What will we do today...
• Questions about the homework? R3 until R9 (skip R6)
• Recap terms and factors
• Recap sum and product
• Recap prime numbers
• We do together: Ch 11: Exercises R1 and R2
• Homework: Ch 11.1 Do Exercises 3, 4, 6, 7, 8
• Exit ticket

#### Slide 1 -Tekstslide

Which exercises should we discuss on the board?

#### Slide 2 -Woordweb

Recap: terms and factors
In the formulas:
y = 2x + 5           p = 7t - 1
2x and 5       &    7t and -1          &                      and                    are called terms.
terms are the "parts" you add up.

In the formula
3, x and 2 are called factors.
factors are the "parts" you multiply
c=10h2h2
10h
2h2
y=3x2

#### Slide 3 -Tekstslide

Recap: Sum and Product
The sum of 2 and 5 is 7.           (2 + 5 = 7)
The sum means you add up the terms.

The product of 2 and 5 is 10.      (2 x 5 = 10)
The product means you mulitply the factors.

#### Slide 4 -Tekstslide

What is the product of 12 and 3?
A
4
B
9
C
15
D
36

#### Slide 5 -Quizvraag

Prime factorisation
Prime numbers are numbers that can only be divided by 1 AND by itself and still have a whole number as a result.

2, 3, 5, 7, 11, 13, 17, ... are prime numbers, because they only have 1 and itself as divisors
12 is not a prime number, because it has 1, 2, 3, 4, 6 and 12 as divisiors.

#### Slide 7 -Tekstslide

Prime factorisation
You can write a number as a product of as many prime factors as possible:
12 = 2 x 2 x 3
21 = 3 x 7
50 = 2 x 5 x 5
80 = 2 x 2 x 2 x 2 x 5

#### Slide 8 -Tekstslide

Prime factorisation
How can you write a number as a product of prime factors?
Option 1:
Write the number as a product of two numbers
Write each of the the tow numbers as a product of two smaller numbers
Repeat untill you only have prime factors.
280 = 10 x 28
280 = 2 x 5 x 2 x 14
280 = 2 x 5 x 2 x 2 x 7

#### Slide 9 -Tekstslide

Prime factorisation
How can you write a number as a product of prime factors?
Option 2:
Divide by the smallest prime number (2) as often as possible
Divide by the next prime number (3) as often as possible
Repeat for 5, 7, 11, etc
280 : 2 = 140
140 : 2 = 70
70 : 2 = 35

#### Slide 10 -Tekstslide

Prime factorisation
How can you write a number as a product of prime factors?
Option 2:
Divide by the smallest prime number (2) as often as possible
Divide by the next prime number (3) as often as possible
Repeat for 5, 7, 11, etc
280 : 2 = 140
140 : 2 = 70                         35 : 5 = 7 (also a prime number)
70 : 2 = 35                         280 = 2 x 2 x 2 x 5 x 7

#### Slide 12 -Tekstslide

Factorising terms with variables
You can also factorise a term such as                   or
by writing the number as a product of prime factors and writing the variable part as a product of variables:

15x2
15x2=35xx
8a3
8a3=222aaa

#### Slide 13 -Tekstslide

HW Thursday
§11.1 Do Exercises 3, 4, 6, 7, 8