1TH/vwo §7.4 Adding and subtracting fractions

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

§7.4 Adding and subtracting fractions.

Fractions??!

Forgotten all about them?

Next slides show you some of those little fellas!

First get organised:

-  open your Notebook and

- put a pen and pencil on your table

- next slide shows you several fractions

A fraction has a ......   and a ....... see below!

The number above is called:   the numerator ( = teller). It tells us: HOW MANY?

The number below is called:    the denominator (= noemer). It tells us the 

TOTAL of the numbers and it's also the NAME.

                       4 = numerator     and                            

                        5 = denominator

​5​​4​​

Finally don't forget to SIMPLIFY the answer, if possible!

However ..... is it always just a piece of cake?

Sometimes it is harder to add or subtract fractions!
That is when the ................ of the fractions are unequal!
Fill in the missing word.

With 'common' denominators 'equal' denominators are meant!

After this example

 it's time for a joke!

1. Copy this task in your Notebook and

2. Work it out.

3. Finally key in your answer in the next slide.

​4​​3​​−​5​​2​​=

​4​​3​​

​5​​2​​

- = ....

explanation:

the new denominator becomes         4 x 5 = 20 !

                     

                   -                     =                           -                            =   

In the next slide we are going to SIMPLIFY.  Just watch!

​4​​3​​

​5​​2​​

​20​​15​​

​20​​8​​

​20​​7​​

The previous subtraction was pretty simple, but .........

......  how to add or subtract fractions like:

 3           and      6          ?

Next slide explains this.

​6​​5​​

​4​​3​​

The following slide ...

Asks for your complete attention, 

as it deals with tricky fractions!               

Unequal denominators and more 

trouble...

A Task for you again!

FOTOVRAAG

1. Copy this task in your Notebook.

2. Work it out and

3. Key in your whole CALCULATION plus ANSWER in the next slide.

5 2/3 + 7/11 = ..........

Solution:

                                                         35, on p.24 is a task, that .....

.... asks for some more attention and time from you!

1st.   Do not only write down the final answer,

but just like in the examples we did together:

WORK THEM OUT, as you've just seen and done!

Good luck.

The last remark is: 'take out the whole numbers'. 

GOOD NEWS:
This is something you DON'T HAVE TO DO!

For example:           is just as good as  1

​3​​4​​

​3​​1​​

Homework time

Do §7.4 yourself now.