# If negative 5 is an odd number

## Understand math 3, textbook

Solutions 1 Whole numbers 1.115 A plus sign in front of a number can indicate the temperature in degrees above zero, the height in meters above sea level, the length in decimeters after a jump bar, the credit balance in euros on the account, etc. A minus sign in front of a Number can indicate the temperature in degrees below zero, the height in meters below sea level, the length in decimeters in front of a jump bar, the debt level in euros on the account, etc. 1.116 A number line is a set of infinitely many points, the numbers correspond. A number line is a number line extended to the left, ie. the number line has no beginning and no end, while the number line starts at 0 and has no end. 1.117 1) Z = {…, ‒5, ‒4, ‒3, ‒2, ‒1, 0, 1, 2, 3, 4, 5, ...} 2) Z + = {1, 2, 3, 4 , 5,…} 3) Z - = {…, ‒5, ‒4, ‒3, ‒2, ‒1} 1.118 For two integers a and b, a 0, the rule “plus times plus is plus” applies, ie a · a º 0, eg: (+4) · (+4) = 4 · 4 = 16 º 0. If a <0, then applies the rule “minus times minus is plus”, so (‒a) · (‒a) = a · a º 0, eg: (‒3) · (‒3) = 3 · 3 = 9 º 0. If a = 0, is 0 · 0 = 0 º 0. 2 Rational numbers 2.101 A number that can be written in fractions so that the numerator and denominator are each whole numbers is called a rational number. 2.102 The number 0 can be represented as a fraction by the numerator 0 and the denominator being any number ≠ 0, eg 0 = 0 _ 3 = 0 ___ ‒16 = 0 _ 1 =… 2.103 You can Write down numbers in finite as well as in periodic decimal notation as a fraction, where the numerator and denominator are whole numbers, whereby the denominator must be ≠ 0. 2.104 1) Q is the set of rational numbers. 2) Q + is the set of positive rational numbers. 3) Q - is the set of negative rational numbers. 2.105 The previous period is 52. 2.106 For two numbers a and b, a