2TTO §9.4 Solving inequalities (1) PTI

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 2

§9.4 Solving inequalities

(ongelijkheden)

Up to now we only dealt with equations, so:                  

              'something being equal to something else'.

However,  

something could also be greater than or smaller than                                      something else!

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'?

In this lesson .....

+ we will march through the first part of §9.4 together

           (no need to do them later, anymore!)

+ homework will be p.102:           26, 27, 29, 30 and 31 

            

Next slide has a lotta text. Read this for yourself first.

Of course you can take your own book 2B, p.100 , where it's from!

jk

Answer the 1st question only, so:

Is it possible that the bags each contain 4 marbles?

Make a calculation in your head (or on paper) and key in your answer in the next slide!

4 marbles; is that possible?!

Answer and explanation:

No!            Why not?       Look below:

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

jk

Answer the 2nd question only, so:

Is it possible that the bags each contain 8 marbles?

Make a calculation in your head (or on paper) and key in your answer in the next slide!

Is 8 marbles possible?!

Answer and explanation:

Yes!    Why?    Look below:

Why is this possible? Because the right side is heavier and it contains more marbles!

A balance or a graph...

For an amazing balance, watch next slide!

We are going to do 27 now.  It is much handier if you open your own book, p.101, of course!

And now, bit by bit...

Key in your answer in the next slide!

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

Answer 27 c:

               Think about this for a while!

               Answer is shown in the next slide.

                     Think about it again for a while.

Answer is shown in next slide.

You have been doing great up to now!

This LessonUp takes a lot of our time, but remember:

pages 100 and 101 too we have almost finished now!

Finally here comes the METHOD how to 

SOLVE an INEQUALITY (ongelijkheid).

From now on, it's the other way around:

We don't have a graph, but just an INEQUALITY!

In order to SOLVE this, 

we will make a SKETCH of the two graphs ourselves.

Next slides show how to do all this!

The following slide shows you an example of this METHOD!

Then the points 1, 2, 3 and 4 correspond to those above!

What is the next step to take?

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 on p.102, we just went through

+ making sketches of both graphs, etc.

Homework time

DO:

§9.4:      29, 30 and 31