Exercise 128 Page 177

Practice makes perfect

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.

1.25(- 3/5)

MultPosNeg

a(- b)=- a * b

- 1.25(3/5)

▼

Write as a decimal

ExpandFrac

a/b=a * 2/b * 2

- 1.25(6/10)

WriteDec

Write as a decimal

- 1.25(0.6)

To find the product, we multiply just as we do with two whole numbers. At first, we ignore any decimal points and negative sign.

Then we place the decimal point in the product by counting the number of decimal places in each factor.

The product of 1.25 and 0.6 is 0.750, or 0.75. This means that the product of 1.25 and - 0.6, which can be also written as - 35, is - 0.75.

Before we evaluate the expression, let's first rewrite the expression so that all of the numbers are fractions.

(- 3 27) 0.14

MixedToFrac

a bc=a* c+b/c

(- 3* 7+2/7) 0.14

WriteAsFrac

Write as a fraction

(- 23/7)14/100

When we multiply fractions, we need to remember that the product of two fractions is equal to the product of the numerators divided by the product of the denominators. Let's find the given product!

(- 23/7)14/100

MultFrac

Multiply fractions

- 23* 14/7* 100

Multiply

- 322/700

ReduceFrac

a/b=.a /7./.b /7.

- 46/100

WriteDec

Write as a decimal

- 0.46

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 both numbers are negative, so the product will be positive. - 4.37(- 5.2)=4.27(5.2) To find the product, we multiply just as we do with two whole numbers. At first, we ignore any decimal points.