1TTO §8.4 Adding and subtracting fractions

§8.4 Adding and subtracting fractions.

Fractions??!

Forgotten all about them?

Next slide shows you some of those little fellas!

Just lean back and let yourself be informed.

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§8.4 Adding and subtracting fractions.

Fractions??!

Forgotten all about them?

Next slide shows you some of those little fellas!

Just lean back and let yourself be informed.

Slide 1 - Diapositive

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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 ​}

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

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

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When is it a bit more work to add or subtract fractions?
What kinda fractions are at stake then?

Slide 9 - Carte mentale

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

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3/4 - 2/5 = ....

Slide 13 - Carte mentale

explanation:

the new denominator becomes 4 x 5 = 20 now!

- = - =

\frac{​ 3 ​ ​}{​ 4 ​}

\frac{​ 2 ​ ​}{​ 5 ​}

\frac{​ 1 5 ​ ​}{​ 2 0 ​}

\frac{​ 8 ​ ​}{​ 2 0 ​}

\frac{​ 7 ​ ​}{​ 2 0 ​}

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But .........

How to add or subtract fractions like:

3 and 6 ?

Next slide explains more.

\frac{​ 5 ​ ​}{​ 6 ​}

\frac{​ 3 ​ ​}{​ 4 ​}

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The following slide ...

Asks for your complete attention,

as it deals with tricky fraction facets!

Unequal denominators and more

trouble...

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Just think hard about this one!

How to do it?! Think about common denominators, of course.

What is the final outcome?

Maybe you'll get the turn to share your answer!

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5 2/3 + 7/11 =

Slide 22 - Carte mentale

Homework time

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