2TH/vwo Ch 1

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 2

This lesson you will:

+ share what you learned 

+ do 2 exercises with a timer and

+ follow the explanations about them and

+ compare to your own results

+ finish the remaining exercises

What did you learn?

Make exercise 39, p.30, now.

You have 2 minutes for this task!

Explanation 39:

a. At 4 km's height it is 

21 - 6 x 4 = -3 degrees Celsius

b. If the height increases by 1 km, then the temperature decreases by 6 degrees Celsius.

c. On the ground it is 21 degrees Celsius, because then h = 0.

d. Then     0 = 21 - 6h, or

6h = 21,  or

h = 21/6 = 3 1/2 

We do care!!

So, at a height of 3 1/2 km it starts to freeze!

Do exercise 45, p.31.

It is some work and not the easiest one, so you get

5 minutes!

When you have earlier, just go on with the other ones.

Eplanation 45:

a. If you do 1500 Crowns x 2 you get 300 Crowns,

however, if you do 54.32 euros x 2, you get 108.64 but that is not in the table. So: not directly proportional!

b. If Crowns go from 3000 to 4000, then

 the cost increase by 141.81 - 106.82 = 35 euros

So the price of one Crown is:

35 : 1000 = 0.035 euros.

c. One Crown costs 0.035 euros, so 

3000 Crowns cost 3000 x 0.035 = 105 euros

The fixed amount is:

106.82 - 105 = 1.82 euros.

d. A good formula to calculate the cost is:

e = 0.035 x C + 1.82

Just carry on doing this §.