1TH/Vwo §7.5 multiplying fractions

§7.5 Multiplying fractions
After   +       and        -     we now look at
the operation:       x   !


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Slide 1: Tekstslide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

In deze les zitten 38 slides, met interactieve quizzen en tekstslides.

time-iconLesduur is: 30 min

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§7.5 Multiplying fractions
After   +       and        -     we now look at
the operation:       x   !


Slide 1 - Tekstslide

§7.5 Vermenigvuldigen van breuken
= huiswerk van vandaag

Slide 2 - Tekstslide

First we multiply a fraction by a whole number:

Slide 3 - Tekstslide

Slide 4 - Tekstslide

Now it's your turn:

Slide 5 - Tekstslide

32
timer
1:00
x 33 = ...

Slide 6 - Woordweb

solution:

Slide 7 - Tekstslide

another one for you:

Slide 8 - Tekstslide

3/13 x 52 = ....
timer
0:25
A
10
B
9
C
14
D
12

Slide 9 - Quizvraag

Solution:

Slide 10 - Tekstslide

Slide 11 - Tekstslide

Now let's talk business:
Finally it's
Fraction times Fraction ...

Slide 12 - Tekstslide

Slide 13 - Tekstslide

2 Important points:
.                        and               .


Slide 14 - Tekstslide

WARNING:
How NOT to MULTIPLY FRACTIONS
watch next slide!

Slide 15 - Tekstslide

Mutiplying fractions in the wrong way:
 COMMON MISUNDERSTANDING; somebody tries to tackle the task below :
 Working with the common denominator: then the new denominator is 14 x 4
              
                x            =         x          =                          x                         ???
1413
43
5652
5642
.............
...............

Slide 16 - Tekstslide

Why does this method really suck?

Slide 17 - Woordweb

SOLUTION:

  When MULTIPLYING fractions with unequal denominators,
    you DON'T have to make them equal!!
Watch the next slides that show how simple it really is!

Slide 18 - Tekstslide

Slide 19 - Tekstslide

Slide 20 - Tekstslide

Slide 21 - Tekstslide

your turn again,
ANS

Slide 22 - Tekstslide

3/8 x 3/8 = ...
timer
0:25
A
9/8
B
9/64
C
6/16
D
3/64

Slide 23 - Quizvraag

Solution:

Slide 24 - Tekstslide

Fotovraag: first COPY it and work it out in your Notebook, take a pic and send in in next slide!
 Show your CALCULATION!





Don't forget to SIMPLIFY your answer, in the end!

Slide 25 - Tekstslide

2/7 + 1/7 x 1/2 = ......
timer
1:00

Slide 26 - Open vraag

Solution:

Slide 27 - Tekstslide

Now it's time for a complicated one:
Tasks:
1. Copy this exercise in your Notebook.
2. Make this exercise.
3. Send in your answer in the next slide.
timer
2:00

Slide 28 - Tekstslide

My answer is:

Slide 29 - Woordweb

This is the Solution:

Slide 30 - Tekstslide

NOTE:
In the final answer you may also give as ONE FRACTION.
So:                 is a good answer, too!
1619

Slide 31 - Tekstslide



For example this one.                                   You might think:
2  x  3 = 6      and                 x          = 

So the final answer is:        6   +        =   6                 However this is WRONG!

21
41
81
81
81

Slide 32 - Tekstslide





Let's look at the next slide for a sec to see what is wrong with the first method!

Slide 33 - Tekstslide

For example this one.                                   You might think:
2  x  3 = 6      and                 x          = 

So the final answer is:        6   +        =   6                 However this is WRONG!
What has been FORGOTTEN here is this:  2 x       and           x 3   !


21
41
81
81
81
41
21

Slide 34 - Tekstslide

FOTOVRAAG:
again COPY it and work it out in your Notebook first and then send it in by a PICTURE:

Slide 35 - Tekstslide

1 1/8 x 1 1/3 = ......
timer
1:30

Slide 36 - Open vraag

Solution:
NOTE:
also          is a perfectly GOOD ANSWER !
23

Slide 37 - Tekstslide

Homework:
§7.5 Make only these tasks:
You may skip:  36 and 38
Send in your CALCULATIONS.
NOTE:  Showing only the answers has no value.
It's about WRITING DOWN the process in LITTLE STEPS!

Slide 38 - Tekstslide