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Copyright © 2011 Pearson Education, Inc. Real Numbers and Their Properties Section P.1 Prerequisites

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-3 A set is a collection of objects or elements. The set containing numbers 1, 2, and 3 is written as {1, 2, 3}. To indicate a continuing pattern, we use three dots as in {1, 2, 3, …}. The set of real numbers is a collection of many types of numbers (an aggregate set of subsets). The Real Numbers

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-4 Subset Name (symbol) {1, 2, 3, …} Counting or natural numbers (N) {0, 1, 2, 3, …} Whole Numbers (W) {…, –3, –2, –1, 0, 1, 2, 3, …} Integers (Z) To better understand real numbers we recall some of the basic subsets of the real numbers: The Real Numbers

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-5 Numbers can be pictured as points on a line, the number line. To draw a number line, draw a line and label any convenient point with the number 0. Now choose a convenient length, one unit, and use it to locate evenly spaced points. The positive integers are located to the right of zero and the negative integers to the left of zero. The numbers corresponding to the points on the line are called the coordinates of the points. The integers and their ratios form the set of rational numbers, Q. The rational numbers also correspond to points on the number line. The Real Numbers

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-6 The set of rational numbers is written as which is read “The set of all numbers of the form a/b such that a and b are integers with b not equal to zero.” Notice that in the set notation above, letters are used to represent integers. A letter that is used to represent a number is called a variable. The Real Numbers

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-7 There are infinitely many rational numbers located between each pair of consecutive integers, yet there are infinitely many points on the number line that do not correspond to rational numbers. The numbers corresponding to points on the number line that do not correspond to rational numbers are called irrational numbers. The Real Numbers

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-8 a + b and ab are real numbersClosure property a + b = b + a and ab = baCommutative properties a + (b + c) = (a + b) + c and a(bc) = (ab)c Associative properties a(b + c) = ab + acDistributive property 0 + a = a and 1·a = a (Zero is the additive identity, and 1 is the multiplicative identity.) Identity properties 0·a = 0Multiplication property of zero For any real numbers a, b, and c: Properties of the Real Numbers

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-9 For each real number a, there is a unique real number –a such that a + (–a) = 0. (–a is the additive inverse of a.) Additive inverse property For each nonzero real number a, there is a unique real number 1/a such that a·1/a = 1. (1/a is the multiplicative inverse or reciprocal of a.) Multiplicative inverse property For any real numbers a, b, and c: Properties of the Real Numbers

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-10 Properties of Opposites For any real numbers a and b: 1. –1 × a = –a (The product of –1 and a is the opposite of a.) 2. –(–a) = a (The opposite of the opposite of a is a.) 3. –(a – b) = b – a (The opposite of a – b is b – a.) Trichotomy Property For any two real numbers a and b, exactly one of the following Is true: a b, or a = b. Additive Inverses and Relations

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-11 Properties of Equality For any real numbers a, b, and c: 1. a = a 2. If a = b, then b = a. 3. If a = b and b = c, then a = c. 4. If a = b, then a and b may be substituted for one another in any expression involving a or b. Reflexive property Symmetric property Transitive property Substitution property Relations

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-12 Definition: Absolute Value For any real number a, Distance Between Two Points on the Number Line If a and b are any two points on the number line, then the distance between a and b is |a – b|. In symbols, d(a – b) = |a – b|. The absolute value of a (in symbols | a |) can be thought of as the distance from a to 0 on a number line. Absolute Value

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-13 Properties of Absolute Value For any two real numbers a and b: 1. (The absolute value of any number is nonnegative.) 2. (Additive inverses have the same absolute value.) 3. (The absolute value of a product is the product of the absolute values. 4. (The absolute value of a quotient is the quotient is the quotient of the absolute values.) Absolute Value

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-14 Definition: Positive Integral Exponents For any positive integer n: We call a the base, n the exponent or power, and a n an exponential expression. We read a n as “a to the nth power.” an n aaaaa of factors Exponential Expressions

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-15 The result of writing numbers in a meaningful combination with the ordinary operations of arithmetic is called an arithmetic expression or simply an expression. The value of an arithmetic expression is a real number obtained when all operations are performed. Symbols such as parentheses, brackets, braces, absolute value bars, and fraction bars are called grouping symbols. Operations within grouping symbols are performed first. Arithmetic Expressions

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-16 1.Evaluate exponential expressions. 2.Perform multiplication and division in order from left to right. 3.Perform addition and subtraction in order from left to right. When some or all grouping symbols are omitted in an expression, we evaluate the expression using the following order of operations. Any operations contained within grouping symbols are performed first, using the order of operations. The Order of Operations

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-17 When we write numbers and one or more variables in a meaningful combination with the ordinary operations of arithmetic, the result is called an algebraic expression, or simply an expression. The value of an algebraic expression is the value of the arithmetic expression that is obtained when the variables are replaced by real numbers. The domain of an algebraic expression in one variable is the set of all real numbers that can be used in place of the variable. Two algebraic expressions in one variable are equivalent if they have the same domain and if they have the same value for each member of the domain. Algebraic Expressions

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P.1 Copyright © 2011 Pearson Education, Inc. Slide P-18 A term is the product of a number and one or more variables raised to whole-number powers. Numbers or expressions that are multiplied are called factors. The coefficient of any variable part of a term is the product of the remaining factors in the term. If two terms contain the same variables with the same exponents, then they are called like terms. The distributive property allows us to combine like terms. To simplify an expression means to find a simpler-looking equivalent expression. The properties of the real numbers are used to simplify expressions. Algebraic Expressions

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