1TH/vwo §9.5 Using cards PART 2

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 1

§ 10.5 Using cards  PART 2

As the Method of SOLVING EQUATIONS is that important,

we do this paragraph in two lessons!

This should make it quite possible for you to work it all out

as the METHOD on p.109 shows you!

 RECAP:

refreshing your memory!

an EQUATION is something like:    23 = 7t + 9

the SOLUTION to this is:  t = 2,  because 23 = 7 x 2 + 9  , or

                                                                                    23 =  14  + 9 

                                                                                    this checks out!

In the previous paragraph you have seen what an equation looks like and how to find a solution.

In this paragraph we will use a method called "using cards" to solve our equation.

You put a card over the term with the variable and decide what number should be written on the card.

Then you know that the term with the variable is equal to that number.

This was a recap from last lesson (1st part of §9.5)

Now the 2nd part comes up:

on p.112 you find tasks that ask from you to:

-  make a formula for a story

-  fill in a number in that formula and finally

-  solve the equation that results from all this

Task 1 follows soon ...

But a JOKE sooner, still!

By the way, the book in the next slide is called:

'How to become a millionaire.'

Task 36 we'll do together right now. 

Let's make it  in your Notebook, now!

+  Let's first read it together.

+ TASK 1:   Make a FORMULA for Kirsten's hair length in cm (= l)  and the months 

     she is growing it (= m). THINK ABOUT THE GENERAL SHAPE OF A FORMULA!

+ One important detail:  12.5 mm = 1.25 cm !

    Use cm only -not mm- in your Formula.

Length Kirsten's hair in a FORMULA
(the numbers 10, 1.25
and the words. length and months
have to be in it!):

Solution Task 1:

TASK 2:   Work out the Question above in your Notebook,

 by FILLING IN the outcome 35 in the FORMULA we just made!

To refresh your memory, here's the FORMULA once more:

l = 10 + 1.25m

Filling in l = 35 in
l = 10 1.25m gives ...

Now we have our formula:

length = 10 + 1.25 x months

It's handier to use a shortened version:

l = 10 + 1.25m

Task 2: Calculate how many months it takes her hair to be at least 35 cm long.

l = 10 + 1.25m

Solution Task 2:

Homework (36 you already made!):

VWO:                    35, 37, C9, C10

H/V:                       35, 37, S34, S35