8-2 The quadratic formulae

• Wiskunde
• Middelbare school
• havo
• Leerjaar 3

8-2 Using the quadratic formula

What you need: - Textbook, writingbook, iPad - Pen, pencil, geotriangle - Calculator

Schoolbags in the cuboard

Phones in the phonebag

Bluetooth 

- ON

- VPN off

                         Lesson goals

Use the quadratic equation to solve equations.

What if factorisation doesn't work

You use the quadratic eqution

First write the equation in the standard form...

So actually the quadratic equation is

but to simplify the calculation we use D

12a

1. a=1 b=5 c=3
2. a=3 b=-5 c=1
3. a=1 b=-5 c=3
4. a=3 b=5 c=1

12b

1. -7
2. 13
3. 21
4. 37

12c

1. x=4,3 or x=-0,7
2. x=4,3 or x=0,7
3. x=-4,3 or x=0,7
4. x=-4,3 or x=-0,7

13a

1. -1
2. 1

13b

1. -32
2. 32
3. 60
4. 64

13c

1. x=6 or x=2
2. x=-6 or x=2
3. x=6 or x=-2
4. x=-6 or x=-2

Try on your own

1, 2, 5 and 7

RULES:

• In your writingbook
• Use: Textbook
• Discussion when you are stuck is allowed

Extra excercise: none

Challenge: 16

HW - correct your mistakes