5.5

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 3

Tuesday 12 January

today:

- homework (25, 26, 27)

- par. 5.5 sum and difference functions

- new homework

homework 25, 26, 27

questions?

ex. 27 together

Read of the period.

1. 0.2
2. 0.8
3. 4
4. 8

What is the average
bloodpressure?

1. 80
2. 90
3. 110
4. 130

What is the amplitude?

Moved or stretched?

1. Moved
2. Stretched

Moved or stretched?

1. Moved
2. Stretched

5.5 sum/difference functions

  

We can make the sum function or  the difference function

of two given functions

sum function: add two functions

difference function: subtract two functions

Skill 5

5.5 sum/difference functions

We can make the sum function or  the difference function

of two given functions

But why??

E.g. economics, physics

And how?

Most easy way: use a diagram 

(like you did in primary school (?))

24

21 +

45  

f(x)

g(x) +

h(x)   

Exercise 29

f(x) = ½x + 2       g(x) = -x + 1

Write down the function s = f + g

f(x) 

g(x) +

s(x)

f(x) =   ½x + 2

g(x) =    -x + 1     +

s(x) = -½x + 3

f(x) = ½x + 2 g(x) = -x + 1
Write down the function s = f - g

1. s(x) = 1½x + 3
2. s(x) = -½x + 3
3. s(x) = 1½x + 1
4. s(x) = -½x + 1

f(x) = ½x + 2 g(x) = -x + 1
Write down the function s = g- f

1. s(x) = -1½x + 3
2. s(x) = -1½x - 1
3. s(x) = ½x - 1
4. s(x) = -½x - 1

Pay attention!

When you subtract 2 functions you have to subtract 

the whole function

f(x) =   ½x + 2     g(x) =    -x + 1  

f(x) - g(x) = ½x + 2 -  (-x + 1)

Homework

Do ex. 30, 31 and 32 of chapter 5

For the drawing, you can use Desmos.