Page 47 - Math Course 2 (Book 1)

Introduction to Real Numbers

Real numbers 1
Name the set or sets of numbers to which 6
irrational numbers and rational numbers together belongs
form the set of real numbers.

Real Number Answer
Rational Number
Rational Numbers Irrational
Numbers Because 1 and 6 are integers and 1÷ 6 = 0.1666…,
Integers which is a repeating decimal, the number is a
rational number.

Whole numbers

Natural numbers Name the set or sets of numbers to which 169
belongs

Answer

Closure property Natural number, whole number, integer and
rational number
is when the result of the addition or multiplication of
two whole numbers is a whole number. Because 169 = 13 this number is a natural
number, a whole number, an integer, and a
rational number.
0 x 4 = 0 5 x 2 = 10 1 + 6 = 7

products or sums of each pair of
whole numbers are whole numbers.

Closure Property
Let’s Begin

Examples

Classify Real Numbers Determine whether each set of numbers is closed
under the indicated operation.

Examples whole numbers, multiplication

The set of whole numbers is
Name the set or sets of numbers to which 17 Answer closed under multiplication.
belongs.

Answer
Determine whether each set of numbers is closed
under the indicated operation.
Irrational number
whole numbers, subtraction
Because 17 = 4.1231056..., which is neither a
repeating nor terminating decimal, this number
is irrational. Answer The set of whole numbers is
not closed under subtraction.

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