Negative Numbers

• Wiskunde
• Middelbare school
• mavo, havo, vwo
• Leerjaar 1

Chapter 9 Negative numbers

Adding a negative number

−3+(−4)=

1. -1
2. 1
3. -7
4. 7

Subtracting a negative number

−3−(−4)=

1. -1
2. 1
3. -7
4. 7

Adding a negative number

3+(−4)=

1. -1
2. 1
3. -7
4. 7

Rules for multiplication

• When multiplying two numbers  with the same signs, the answer is always positive.
  
  
• When multiplying two numbers  with different signs, the answer is always negative.

Multiplying numbers
-5 x -4 =

1. 20
2. -20

Multiplying numbers
7 x -4 =

1. -28
2. 28

Multiplying numbers
-5 x 0 =

1. -5
2. 0

Rules for division

• When dividing two numbers with the same sign, the answer is always positive.
  
  
• When dividing two numbers with different signs, the answer is always negative.

a negative number divided by a positive number equals

1. a positive number
2. a negative number

Dividing numbers
-28 : -4 =

1. -7
2. 7

Dividing numbers
-7 : 1 =

1. -7
2. 7
3. -1
4. 1

Task 1:

Key in your answer in the next slide!

Who's right?
Paulo says: 9
Sabine says: -9

1. Sabine
2. both
3. Paulo
4. neither

explanation:

Task 2:

-           = 25    (A)

-           = - 25   (B)

-           = 10      ©

-           = - 10     (D)    Fill in the good answer in the next slide.

5​2​​

5​2​​

5​2​​

5​2​​

minus five squared equals ......

1. 25
2. - 25
3. 10
4. - 10

minus five squared equals ......

1. 25
2. - 25
3. 10
4. - 10

explanation:

-         =    -  5 x 5 = - 25

So the key to the answer is that only 5 is squared, but not

the minus sign!!

Time for a bit of Theory!

5​2​​

Task 3:

=  .....

Fill in your answer in the next slide, again.

(−4)​3​​

(−4)​3​​

(−4)​3​​

(−4)​3​​

1. 64
2. -64
3. -12
4. 12

Explanation Task 3:

=  -4 x -4 x -4 = -64

(−4)​3​​

Task 4: 

in the same way do:

=  ............

−4​3​​

Task 4:

1. -64
2. -12
3. 12
4. 64

Explanation Task 4: 

=        -   4 x 4 x 4 = -64

So, do               and             

give the same outcome?!

Indeed, they do!!        

−4​3​​

(−4)​3​​

−4​3​​

Think hard about this one:

This is the Solution:

Start prepare for the test:

Test yourself or

Extra exercises or

Practice test (in your workbook)