2TH §4.6 Test Preparation

• Wiskunde
• Middelbare school
• havo
• Leerjaar 2

CH4 Roots

Summary

Roots

You know what a square root is.

The square root of 25 is 5 because 5 x 5 = 25. 

You cannot take the square root of a negative number.

Adding and Subtracting Roots

You can only add and subtract roots with the same number underneath the square root sign. This works the same way as adding and subtracting like terms.

Write as short as possible

P=15√​a​​​+6√​b​​​+5√​a​​​−2√​b​​​

1. P=20√​a​​​+8√​b​​​
2. P=24√​ab​​​
3. P=20√​a​​​+4√​b​​​
4. cannot be written any shorter

Write as short as possible

y=3√​x​​​−6√​2​​​+6√​x​​​−2√​2​​​

1. y=9√​x​​​−4√​2​​​
2. y=9√​x​​​−8√​2​​​
3. y=−3√​x​​​+4√​2​​​
4. Cannot be written any shorter.

Multiplying square roots

We've seen that

because: 

 area of the square =               x            =               = 5

As a rule we say:

√​5​​​

√​5​​​

√​25​​​

Multiplying square roots

When multiplying square roots, you use the rule

If there are numbers in front of the square roots, you multiply those by each other.

What's under the chocolate milk?

Write as short as possible

1. 6√​32​​​
2. 3√​64​​​
3. 24
4. cannot be written shorter

Write as a single square root

You can write numbers as a single square root.

This makes it easier to compare numbers.

Simplify square roots

When you simplify a square root, you rewrite the root so you get the smallest possible whole number underneat the root sign.

Simplify if possible

1. 2√​180​​​
2. 12√​10​​​
3. 12
4. cannot be simplified

Solution

Exact or Approximation

When asked for an exact answer, you give your answer as a square root (or a whole number if the square root is a whole number).

When asked for an approximation you type the square root in your calculator and round off the result.

Test Preparation

• Make your cheat sheet
• Do the Mixed exercises (page 148-149) 
• Do Summary Learning goals | Extra exercises (page 150-155)
• Do the Practise Test (page 156-157)

(not anything with cubic roots)

HAND IN YOUR CHEAT SHEET AT THE END OF THE LESSON!!

Which theories/exercises should I discuss on the board?