1TH/vwo §6.4 Formulas from graphs 1st Form (short version)

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 1

§6.4 Making a FORMULA from a GRAPH

For this graph...

... we cannot make a formula, sadly enough.

For wat kind of GRAPH can we make a FORMULA?

1. a graph that goes up and down
2. a linear graph
3. a graph that has the form of a circle
4. a straight line

Maybe this Theory doen't explain much to you...

That's  why a few EXAMPLES follow.

One about a RISING GRAPH and one about a 

FALLING GRAPH.   

A STRAIGHT LINE = our type of graph!

Look at the following slide. For this Graph we CAN

make a Formula! 

Example 1

Example 2: As you see, we have a falling graph here.

Let's call the horizontal axis a and the vertical axis b.

Step 1.   Above you see the table with 3 points from the graph.

Let's call the horizontal axis a and the vertical one b.

Step 2.  The graph starts at height 5 on the vertical axis. So that's the starting value.

Step 3.  When the graph goes to the right 1 step, it goes down 2 steps.

Step 4.   Putting steps 2 and 3 in the shape of a Formula:   

                 b = 5  -  2 x a

Let us Study the Theory one more time!

            

a	0	1	2
b	5	3	1

TASK:

Make a FORMULA for the GRAPH on the next slide.

Get a pen, pencil and geo and open your Notebook.

Use the METHOD you just saw.

Forgotten all about it?

It's on p.216 in your Textbook!

step 1.Above you see the Table, 

that contains 3 points from the graph.

Let's call the axes:         a and b.

step 2.  The starting value is 5, because at that height the

                graph starts at the vertical axis.

step 3.  If you go 3 steps to the right, then you go down 2 steps.  So:

                If you go 1 step     to the right, then you go down       of a step.

step 4.  The Formula becomes:  b = 5 -     x a

               

            

x	0	3	6
y	5	3	1

​3​​2​​

​3​​2​​

The + and - signs make a huge difference:

PRACTICE PRACTICE PRACTICE ...

Now it's time you make a FORMULA for a GRAPH yourself!

FOTOVRAAG- to be handed in, in the next slide!

- have you got your:

   1. Notebook   2. pencil   3. geo  4. eraser    before you?

- if not, get it right now!

- the task starts; 

   1. make it in your Notebook   2. take a pic   3. send it in in!

Use the Method from p.218 

again!

FOTOVRAAG

28a - my work on Andrews' Formula:

Solution:

Homework time.

You may skip 25 and 26

Make §6.4 now.   Don't forget to:

+  check your work with the Solutionsbook

+  take a few pictures of it

+  send them in in GC