2Tvwo § 5.4 Quadratic formulas 1!

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• Middelbare school
• vwo
• Leerjaar 2

§ 5.4 Quadratic formulas

Let's see what you've learned from § 5.3 Shortening formulas !

How to do the coming tasks? (1)

Open you Notebook on an empty page,

write: 

'§5.3 - Practice: '

Use a Multiplication Table or The Parrot's beak!

How to do the coming tasks? (2)

COPY the coming tasks first,

then WORK IT OUT

Use a Multiplication Table or The Parrot's beak!

Question 1

Write as short as possible:

4a (5a - 3) + 5 = ..................

my answer is:
(write 'squared' just as 'squared')

Answer 1

4a (5a - 3) + 5 =

20a² -12a + 5  

Question 2-FOTOVRAAG!

Write as short as possible:

y = (2x + 4) (-x + 6) - 5x

1. Again, first COPY the task.

2. Then WORK IT OUT work it out on paper.

3.  Finally take a Picture of your work (not just the answer).

4.  Send it in in the next slide!

Task 2, My work:

Answer 2

y = (2x + 4) (-x + 6) - 5x 

y =          + 12x -4x + 24 - 5x 

y =            +3x + 24

−2x​2​​

−2x​2​​

Question 3

(2a -6)²  

TIP- use this method :

p​2​​=p⋅p

Answer 3

   (2a - 6)² =                                 

   (2a - 6) (2a - 6) = 

   4a² - 12a - 12a + 36 =        

    4a² - 24a + 36

 

Question 4 (about § 5.4 now)

y = - x² 

+ Fill in x = -7   in the given Formula.

+ COPY the task and 

+ WORK it OUT in your Notebook.

Answer 4

    y = - x²         (Watch the brackets:)

  y = - (-7)² = - -7 x -7 = 7 x -7 = -49

(When you square a negative number, you need brackets!)

Some THEORY now!

Lollipopsticks decide...

who'll read this for us.

Whoever it is, please read it clearly and slowly, so we have the time to follow everything carefully!

It's a lotta new stuff and we need some time to digest it. 

 question about exercise 29:

Question 5:

Watch the TABLE of 29 and think:

 What is a handy thing to use for this GRAPH ?

Answer 5

The numbers on the Vertical axis go from 195 to 320,

so you need a:

ZIGZAG!

 Question 6

Exercise 29, once more:

What could be a good scale for this Graph?

Answer 6

A good scale would be:    20 metres in 1 cm

Why? Watch this:

320 - 195 = 125

125 : 20 = 6.25, so then you take a vertical axis of 7 cm and that is fine.

Homework Time

Do § 5.4, skipping: 24 and 25.

Use your PENCIL + GEO for drawing the GRAPHS.

Check and Correct with the Solutionsbook.

Good luck!

What did you learn this lesson?