# 1TH/Vwo §6.5 Comparing graphs

§6.5 Comparing graphs
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Slide 1: Slide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

This lesson contains 31 slides, with interactive quizzes and text slides.

Lesson duration is: 50 min

## Items in this lesson

§6.5 Comparing graphs

Good morning!

#### Slide 2 -Slide

Good morning, everybody!

#### Slide 4 -Slide

Let's go through an exercise!

#### Slide 5 -Slide

exercise
This graph shows you
the cost when
hiring a lawn mower
(=grasmaaier).

#### Slide 6 -Slide

exercise
Because 2 graphs are drawn in 1
coordinate system,
we can COMPARE them!

#### Slide 7 -Slide

exercise
After how many days is the price
you pay at Praxis
the same as at Finefix?
Key in in next slide.

#### Slide 8 -Slide

After how many days is the price
you pay at Praxis
the same as at Finefix?

#### Slide 9 -Open question

exercise
So for 4 days the prices are equal. Both
companies then charge 50 euros.
We call the point (4, 50)
the Point of Intersection (= snijpunt)!

#### Slide 10 -Slide

exercise
If you hire a lawn mower
for 2 days, which company is
cheapest?

#### Slide 11 -Slide

For 2 days ....
A
better choose for Praxis
B
it depends
C
better choose for Finefix
D
doesn't matter

#### Slide 12 -Quiz

Explanation exercise ,
If you hire a lawn mower for 2 days, what is
the cheapest?
1. Go to '2 days' on the horizontal axis.
2. Go up and see which graph is highest.
3. Well, Finefix' graph lies lower,
4. so Finefix is cheapest for 2 days!

#### Slide 14 -Slide

exercise
If you hire a lawn mower for 5 days,
which company is cheapest then?
Key in in next slide.

#### Slide 15 -Slide

For 5 days ...
A
Praxis is cheapest.
B
Doesn't matter.
C
Finefix is cheapest.
D
idk

#### Slide 16 -Quiz

Explanation exercise 32,
If you hire a lawn mower for 5 days,
which company, which is cheapest?
Go to 5 days on the horizontal axis.
Go up and see which graph lies lowest.
Praxis' graph is lowest for 5 days,
so then the price is lowest too!

#### Slide 17 -Slide

exercise
Which graph has a fixed amount?
(That is the amount you have to pay,
no matter how many days they will work
for you!)

#### Slide 18 -Slide

A fixed amount ...
A
Graph for Praxis has one.
B
No clue at all.
C
Graph for Finefix has one.
D
Both graphs have one.

#### Slide 19 -Quiz

Explanation exercise ,
Which graph has a fixed amount?
The graph for Praxis starts at 10 euros.
That's what you have to pay before you have used
this carpet cleaner for even one minute!
That's why we call this a FIXED AMOUNT.
The amount is fixed, no matter how long you use it.

#### Slide 20 -Slide

Question: What to do first, when making this task ?
ANS

#### Slide 21 -Slide

First you have to ....

#### Slide 22 -Mind map

Solution:
Make a TABLE, indeed!
In exercises 33a. and  34a  they ask you to make a graph from a formula.
Also for those tasks MAKE a TABLE first!
How else do you know which points lie on the graph?!
However, a TIP for this follows now.

#### Slide 23 -Slide

This is how the
SOLUTIONSBOOK does it.
However, why including so may points in the TABLE?
They all lie on the same straight line!
So 3 or 4 points will be enough. For example number 0, 10 and 16.

#### Slide 24 -Slide

The two graphs have a point
of intersection.
I read off:   (5, 3.5) is the p.o.i.
However, it is NOT a grid point, so I cannot be sure.
Fortunately I can also CALCULATE the coordinates!

#### Slide 25 -Slide

If you have no clue what is meant here,
watch the following slides! You will see:
- two graphs that have a point of intersection
- after this the FIRST COORDINATE will be FILLED in in
both FORMULAS, to see if we get THE SAME ANSWER!

#### Slide 28 -Slide

In this lessonup you have learned .....
I'd much better ASK YOU, what you've learned!
Think of a 'general description' (=algemene beschrijving) for what you learned.

#### Slide 29 -Slide

I have learnt ...

#### Slide 30 -Mind map

Homework time
Make §6.5. You may skip 30.
- correct with Solutionsbook