# 2Tvwo §9.4 Solving inequalities (1)

§9.4 Solving inequalities
(ongelijkheden)
Up to now we only dealt with equations, so:
'something being equal to something else'.
2c + 5 = 6c
However,
something could also be GREATER THAN or SMALLER THAN                                      something else!
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Slide 1: Tekstslide
WiskundeMiddelbare schoolvwoLeerjaar 2

In deze les zitten 37 slides, met interactieve quizzen en tekstslides.

Lesduur is: 50 min

## Onderdelen in deze les

§9.4 Solving inequalities
(ongelijkheden)
Up to now we only dealt with equations, so:
'something being equal to something else'.
2c + 5 = 6c
However,
something could also be GREATER THAN or SMALLER THAN                                      something else!

#### Slide 1 -Tekstslide

Below you see what you will learn and the kind of tasks
you are going to solve. But how?!

Do you remember the signs:
for 'smaller than'       and
for 'greater than'?

#### Slide 2 -Tekstslide

In this lesson .....
+ we will march through the first part of §9.4 together
+ homework will be p.102:           29, 30 and 31
(only 3 exercises? Yes, but this is still a lotta work!)
Next slide has a long text. Read this for yourself first.
Of course you can take your own book 2B, p.100 , where it's from!

#### Slide 3 -Tekstslide

jk
Answer the 1st question only, so:
Is it possible that the bags each contain 4 marbles?

A
yes
B
no

#### Slide 5 -Quizvraag

No!            Why not?       Look below:

Keep in mind that the left side is heavier, so it contains more marbles!

#### Slide 6 -Tekstslide

jk
'Is it possible that the bags each contain 8 marbles?'
Make a CALCULATION in your NOTEBOOK

#### Slide 7 -Tekstslide

timer
1:00
Is 8 marbles possible?!

#### Slide 8 -Woordweb

The good answer is:                Yes!              Explanation follows:

Why is this 8 marbles a good answer?
Because the left side then is heavier as it contains more marbles!

#### Slide 9 -Tekstslide

A balance or a graph...

For an amazing balance, watch next slide!

#### Slide 11 -Tekstslide

We are going to do 27 now.  It is much handier to work from the paper book, p.101, of course!

#### Slide 12 -Tekstslide

And now, bit by bit...

Work out in your Notebook now!
timer
1:30

timer
0:30

Solution:

#### Slide 16 -Tekstslide

Make in your Notebook and then
timer
1:00

#### Slide 17 -Tekstslide

Graph A is steeper because ...
(tell from the formulas!)

#### Slide 19 -Tekstslide

Make in your Notebook and compare a bit later!
timer
0:30

Solution:

#### Slide 21 -Tekstslide

compare, soon.

timer
0:30

#### Slide 24 -Tekstslide

You have been doing great up to now!
This LessonUp takes a lot of our time, but remember:
pages 100 and 101 we have almost finished now!

Finally here comes the METHOD how to
SOLVE an INEQUALITY (ongelijkheid).

#### Slide 25 -Tekstslide

From now on, it's 'the other way around':
We DON'T HAVE A GRAPH, but just an INEQUALITY!
Oh dear, how sad, never mind... There's  great SOLUTION to this 'problem':
In order to SOLVE this,
we will MAKE a SKETCH of the two graphs ourselves.
Next slides show how to do all this!

#### Slide 26 -Tekstslide

The first two steps are done in order to:
calculate the point of intersection (=p.o.i.) of the graphs!
The following slides shows you an example of this METHOD!
Then the points 1, 2, 3 and 4 correspond to those above!

#### Slide 27 -Tekstslide

It asks for all the x numbers for which the GRAPH for
y = x + 10 lies higher than the one for y = 2x + 2
There's some work to be done for this, as we don't have the graphs?! Next slides explain it all!

#### Slide 31 -Tekstslide

What is the next step to take?

#### Slide 35 -Tekstslide

After all is said and done ...
There are exercises 29, 30 and 31 to be done by yourself.
In 29 and 30 no graphs are given, so just
+ work out the 4 points from the Method we just went through;
+ this Method is there for you on pages 101 and 102!

#### Slide 36 -Tekstslide

Homework time
DO:
§9.4:      29, 30 and 31