2TH §5.3 Shortening formulas

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• Middelbare school
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• Leerjaar 2

Which exercises/theories should we discuss on the board?

Today's program

Questions about the homework? §5.2 Exercises 9, 11, 12, 13b  

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Refresh: Removing single and double brackets

What will we learn today? Shortening formulas

• Let's do this together

• Draw arcs to show what multiplication you're doing.
• Work this out in your notebook

Removing single brackets

In §5.1 you learned how to write a formula such as y = 2t(3t + 4) without brackets, by thinking of the formula as the area of a rectangle with a side of 2t and a side of 3t + 4.

You could also work this out with a multiplication table or by drawing arcs.

               Rectangle                             Multiplication table             Arcs

Removing double brackets

In the same way, you can write formulas such as y = (2t + 3)(3t + 4) without brackets. Think of a rectangle with a side of 2t + 3 and a side of 3t + 4.

Removing double brackets

The area is 

So 

can be written without brackets as

Removing double brackets

You can draw arcs to show what multiplications you are doing. This is called the "parrot beak" method.

Example:

Shortening formulas

Let's do this together

HW Monday

 §5.3 Do exercises 18, 19, 20 and 22

Don't forget to check and correct your answers with the Solutions book

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