# 2TH/vwo §1.3 Making linear formulas

§1.3 Making linear formulas
Goal of this paragraph:
How to make a formula for a straight line that describes a relation between x and y.
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Slide 1: Tekstslide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 2

In deze les zitten 22 slides, met interactieve quizzen en tekstslides.

Lesduur is: 45 min

## Onderdelen in deze les

§1.3 Making linear formulas
Goal of this paragraph:
How to make a formula for a straight line that describes a relation between x and y.

#### Slide 1 -Tekstslide

1st           a freshen up:
The formula for a straight line is called a LINEAR FORMULA.
The graph for the formula s = 15 - 3a is a straight line.
This is taken from §1.1 Linear relations.
Next slide shows you the graph too!

#### Slide 3 -Tekstslide

2nd:         we make an example of a linear formula:
-  Suppose we, as a class and a teacher, go on a rowing trip on the
Ijsselmeer.
-  The fixed amount (the money we have to pay, no matter how many boats are hired) is 15 euros.
-  The number of boats we hire we call b.
-  Every boat costs 5 euros.
-  The total cost for the trip we call c.
-  In the next slide CHOOSE the RIGHT FORMULA for this trip.

#### Slide 4 -Tekstslide

The right formula is:
timer
0:20
A
c = 15b + 5
B
15 + 5b = c
C
c = 15 + 5b
D
b = 15c + 5

#### Slide 5 -Quizvraag

B        15 + 5b = c    and
C         c = 15 + 5b

#### Slide 7 -Tekstslide

3rd:   Now we have a graph of a straight line.
How to make a linear formula?   Next slide shows you how!

#### Slide 8 -Tekstslide

The next slide shows you

The next slide describes which steps were taken.

#### Slide 9 -Tekstslide

This is what has been done:
15.06.28

#### Slide 10 -Tekstslide

You make
the formula!
STEP 1:
Choose the correct
points in the
next slide.

#### Slide 11 -Tekstslide

Correct points are:
A
(15, 0)
B
(0, 5)
C
(0, 15)
D
(5, 0)

STEP 2:
Calculate the

timer
0:30

timer
0:15

#### Slide 14 -Woordweb

STEP 2:
Solution:
-15 / 5 = -3
because the graph is falling!

STEP 3:
y-intercept.
the next slide)

A
5
B
15
C
(0, 15)
D
(15, 0)

#### Slide 17 -Quizvraag

STEP 3:
Solution:
15 is the y-intercept.
Not (0, 15), because
it is a NUMBER and
not a POINT!

#### Slide 18 -Tekstslide

And the
FORMULA is ......
Choose the
good one.
ANS

The formula is:
A
y = -15 + 3x
B
y = 15 - 3x
C
y= -3x + 15
D
y = 3x - 15

#### Slide 20 -Quizvraag

And the
FORMULA is ......
y = -3x + 15  or
y = 15 -3x

#### Slide 21 -Tekstslide

Homework:
+  When making formulas, write down the 4 steps you learnt!
+   Vwo  choose the Standard or Challenge  path
+  Check your Homework with the Solutionsbook and
+  Make some pictures of it and send them in, in GC