1TH/vwo §7.4 Adding and subtracting fractions

§7.4 Adding and subtracting fractions.

Fractions??!

Forgotten all about them?

Next slides show you some of those little fellas!

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Slide 1: Diapositive

WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

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§7.4 Adding and subtracting fractions.

Fractions??!

Forgotten all about them?

Next slides show you some of those little fellas!

Slide 1 - Diapositive

First get organised:

- open your Notebook and

- put a pen and pencil on your table

- next slide shows you several fractions

Slide 2 - Diapositive

Slide 3 - Diapositive

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

\frac{​ 4 ​ ​}{​ 5 ​}

Slide 4 - Diapositive

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

Slide 5 - Diapositive

Slide 6 - Diapositive

Slide 7 - Diapositive

Slide 8 - Diapositive

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

Slide 9 - Diapositive

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

Slide 10 - Carte mentale

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

Slide 11 - Diapositive

Slide 12 - Diapositive

After this example

it's time for a joke!

Slide 13 - Diapositive

Slide 14 - Diapositive

1. Copy this task in your Notebook and

2. Work it out.

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

\frac{​ 3 ​ ​}{​ 4 ​} - \frac{​ 2 ​ ​}{​ 5 ​} =

timer

1:00

Slide 15 - Diapositive

\frac{​ 3 ​ ​}{​ 4 ​}

\frac{​ 2 ​ ​}{​ 5 ​}

- = ....

Slide 16 - Carte mentale

explanation:

the new denominator becomes 4 x 5 = 20 !

- = - =

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

\frac{​ 3 ​ ​}{​ 4 ​}

\frac{​ 2 ​ ​}{​ 5 ​}

\frac{​ 1 5 ​ ​}{​ 2 0 ​}

\frac{​ 8 ​ ​}{​ 2 0 ​}

\frac{​ 7 ​ ​}{​ 2 0 ​}

Slide 17 - Diapositive

Slide 18 - Diapositive

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

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

3 and 6 ?

Next slide explains this.

\frac{​ 5 ​ ​}{​ 6 ​}

\frac{​ 3 ​ ​}{​ 4 ​}

Slide 19 - Diapositive

Slide 20 - Diapositive

Slide 21 - Diapositive

The following slide ...

Asks for your complete attention,

as it deals with tricky fractions!

Unequal denominators and more

trouble...

Slide 22 - Diapositive

Slide 23 - Diapositive

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.

timer

1:30

Slide 24 - Diapositive

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

Slide 25 - Question ouverte

Solution:

Slide 26 - Diapositive

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.

Slide 27 - Diapositive

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

\frac{​ 4 ​ ​}{​ 3 ​}

\frac{​ 1 ​ ​}{​ 3 ​}

Slide 28 - Diapositive

Homework time

Do §7.4 yourself now.

Slide 29 - Diapositive

Slide 30 - Diapositive