1Tvwo §11.1 Addition and subtraction

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

Ch 11 Calculating with variables

Today we will do:

§ 11.1 Addition and subtraction,

so:   +   and    -

You can shorten a formula .....

By adding " Like terms" together or by subtracting " Like terms" from each other

But what are like terms?

They are the terms that have the same variables.

By the way, 'just numbers', so without any variables, are also like terms:

8 + 9 = 17.  Here 8 and 9 are like terms that you can add together.

Examples

h = 4r + 2r  there are 2 terms both with variable r

so adding them gives h = 6r

b = 2a + 7a -10 here there are 3 terms but only 2a and 7a are like terms

so we get      b = 9a -10

p = 4 + 6 + 2s

p = 10 + 2s ( we cannot add 10 to 2s)

A few tasks for you ...

Shorten:
k = -4 + 6k -6

1. k = 10 + 6k
2. k = 6k - 10
3. k = -10 + 6k
4. k = 16k

Solution:

k = -4 + 6k -6         The like terms are the terms we like.

                                    The like terms here are -4 and -6.

k = -10 + 6k    or  also:    k = 6k - 10           

 Attention: in 'Ch8 Negative numbers' you                                                                             learned that -4 -6 = -10

                                     however:      -4 x -6 = 24 (so: positive!)

t = -5k - 5 + 3k + 7
Shorten again!

1. t = 2k + 2
2. t = -2k + 2
3. t = -2k - 2
4. t = -4k

Solution:

t = -5k - 5 + 3k + 7              Taking the like terms together gives:

t = -2k + 2                              

  Finally: -2k and 2 are not like terms,

                                                    so you cannot add them together.

Open your Notebook and get a pen, for the following task!

Answer this question 

in your Notebook!

Solution:

Do exercises b and c in your notebook

Answer c in the next slide

Also give your answer in the next slide.

SHORTEN:
P = ........ + ........b

Solution:

High time ...

for a Joke.

Think about question 5b!

Choose in next slide.

The answer to question 5b is:

1. 1st formula corresponds
2. 2nd formula corresponds

Homework:

Choose your path: