Exercise 1 Page 84

When multiplying real numbers, the product will be positive if the signs are the same and it will be negative if the signs are different. cc Same Sign & Different Signs (+)(+)=(+) & (+)(-)=(-) (-)(-)=(+) & (-)(+)=(-)In our case one number is positive and one number is negative, so the product will be negative.

- 9(2)

MultNegPos

(- a)b = - ab

-9*2

Multiply

Multiply

- 18

We can verify this using a calculator.

Extra

Properties of Operations

Some important properties that can help us understand why the multiplication of real numbers works the way that it does are the Associative Property of Multiplication and the Commutative Property of Multiplication.

Associative Property	(a* b)* c = a* (b* c)
Commutative Property	3a* b = b * a

Let's look at how the Associative Property can help us understand the given exercise.

- 9(2)

Rewrite

Rewrite negative as -1

- 1 * 9(2)

AssociativePropMult

Associative Property of Multiplication

-1* (9*2)

Multiply

Multiply

-1 * 18

Multiply

Multiply

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