Any questions on today’s homework. (Sections 1. 6/1 Any questions on today’s homework? (Sections 1.6/1.7) Reminder: You should be doing this homework without using a calculator, because calculators can’t be used for Quizzes 1 or 2, Test 1 or the Gateway Quiz.

Quiz coming up next week: Gateway Quiz Try #1 8 questions Online quiz with paper worksheet no calculator Worth 80 points (only your best score of the semester counts) You have had a number of practice Gateway questions mixed in with your regular homework assignments, but you should also take Practice Gateway Quiz 1 before the next class session: 8 questions on the practice Gateway, same type as on the actual Gateway You can take the practice Gateway as many times as you want, and only your best score counts for points. (Practice Gateway is worth 8 points) Additional paper versions of practice Gateways can be picked up in the open lab from any TA or teacher. REMEMBER: Gateway study help available every MTWTh in Room 203 JHSW.

Quiz coming up the class session after Gateway Quiz 1 on sections 1.2 through 1.8 15 questions; 50 minute time limit Taken in class, but via the online course web site Worth 60 points 1 attempt No calculators allowed Practice Quiz 1 should be taken at least 2-3 times before the quiz day: 19 questions; 50 minute time limit; can take it anywhere Worth 10 points Unlimited attempts, only best score counts Each time you take it, you will get a different set of questions, so the more times you take it, the more chances you’ll have of seeing all the types of questions that might be on the real quiz. Don’t use a calculator, since you can’t on the real quiz. REMEMBER: Come to the open lab in 203 if you need help.

Next Class Session: Two assignments due at the start of the next class session: 1. HW 1.2/1.8 2. Gateway HW #2 (paper worksheet required!) In Class: Lecture: Review for Gateway Quiz 1 (this online quiz will be given at the next class session after this review lecture) Practice: Take a Preview Gateway Quiz during last half of class session (worth 8 points, for extra practice).

NOW CLOSE YOUR LAPTOPS (You may reopen them when I finish the lecture, at which time you can start this homework assignment.)

Section 1.2 Sets of numbers: Natural numbers: {1, 2, 3, 4, 5, 6 . . .} (These are also called the “Counting Numbers” – think about how you count out loud: 1, 2, 3,… Whole numbers: {0, 1, 2, 3, 4 . . .} (Just add the number zero to the natural numbers) Integers: {. . . –3, -2, -1, 0, 1, 2, 3 . . .} (All positive and negative counting numbers and zero)

More sets of numbers: Rational numbers – the set of all numbers that can be expressed as a ratio (or quotient) of integers, with denominator  0. (In other words, any number that can be written as a fraction or a ratio.) Comments on the set of rational numbers: All integers are also rational numbers, because to make them into a fraction, you just write 1 on the bottom (the bottom number is called the denominator, top number is called the numerator.) If you divide the numerator by the denominator on your calculator, you will get a decimal number that either ENDS or REPEATS. Examples: 1 = 0.25 8 = 1.6 -2 = -0.666 2 = 0.181818… 4 5 3 11

More sets of numbers: Irrational numbers – the set of all numbers that can NOT be expressed as a ratio of integers (“irrational” literally mean “NOT rational” _ Examples: Π , √2 These numbers CAN’T be expressed as a fraction, and their decimal form never ends and never repeats. (Try entering these numbers on a scientific calculator and you’ll see this behavior.)

And one last set of numbers (the big one…): Real numbers – the set of all rational and irrational numbers combined Comments about the real numbers: When you draw a number line, every point on the line is associated with a real number – the number tells how far the point is from zero, the middle of the number line. A negative number means the point is to the LEFT of zero on a number line; positive numbers are to the right of zero. The actual DISTANCE of a point from zero is called the ABSOLUTE VALUE of the number, and it’s always positive (except of course the number zero, whose absolute value is just zero – more on this later today.) 2 – 2 1 3 4 5 – 1 – 3 – 4 – 5 Negative numbers Positive numbers

Page 11 in your online textbook (same in hardcopy version) provides a helpful diagram of all these number sets and their relationships to each other. Underneath this diagram on page 11 are some example problems (EXAMPLE 5) that will be useful in preparing to do the homework problems.

Example from homework: Choose which group of sets the following number belongs to. Be sure to account for ALL sets. 2 9 Real numbers, rational numbers Real numbers, irrational numbers Real numbers, rational numbers, natural numbers Rational numbers, natural numbers, integers Irrational numbers, natural numbers Answer: A

A number line used to represent ordered real numbers has negative numbers to the left of 0 and positive numbers to the right of 0. Order Property for Real Numbers indicates how to use inequality signs (< , which means “less than”, and >, meaning “greater than”). If a and b are real numbers, a < b means a is to the left of b on a number line. a > b means a is to the right of b on a number line.

Examples: Fill in the blank with either < or > : 3 ___ 10 -2 ___ 5 -2 ___ -5 (be careful on this one!) -5 ___ -2 When in doubt, draw the two numbers on a number line. If the first number is farther LEFT, put in the < sign. If the first number is to the RIGHT of the second one, put in the > sign.

The absolute value of a number is the distance of that number away from 0. a 0, since distances are non-negative. Note:  means “greater than or equal to”, so “ 0” really just means “not negative”, i.e. “either positive or zero”

Sample problems: find the absolute value: |3| = 3 |-3| = 3 |0| = 0 |- ½ | = ½ -|-3| = -3 Fill in the blank with either < or > : |3| ___ |10| |-2| ___ | 5 | |-2| ___ |-5| |-5| ___ |-2| (be careful on this one!) -|-5| ___ -|-2| (and this one!) When in doubt, draw the two numbers on a number line. If the first number is farther LEFT, put in the < sign. If the first number is to the RIGHT of the second one, put in the > sign.

Example from homework: Rewrite the inequality so that the inequality symbol points in the opposite direction and the resulting statement has the same meaning as the given one. 6<16 Answer: 16 > 6

Section 1.8 Properties of real numbers Commutative property of addition: a + b = b + a of multiplication: a · b = b · a Examples: Complete each statement using the commutative property: x + 16 = __________ Answer: 16 + x xy = _______ Answer: yx

More properties of real numbers: Associative property of addition: (a + b) + c = a + (b + c) of multiplication: (a · b) · c = a · (b · c) Examples: Complete each statement using the associative property: (x + 16) + 2y = __________ Answer: x + (16 + 2y) 4·(xy) = _______ Answer: (4x)·y

More examples: Use the commutative and associative properties to simplify: 8 + (9 + b) Solution: 8 + (9 + b) = (8 + 9) + b = 17 + b 2(42x) Solution: 2(42x) = (2·42)x = 84 x 13 + (a + 13) Solution: 13 + (a + 13) = 13 + (13 + a) = (13 + 13) + a = 26 + a

Distributive property of multiplication over addition a(b + c) = ab + ac Examples: Use the distributive property to write each statement without parentheses, and then simplify the result where possible: 8(x + 2) Solution: 8(x + 2) = 8·x + 8·2 = 8x + 16 -2(3x – 4y + 7) Solution: -2(3x – 4y + 7) = -2·3x + -2·(-4y) + -2·7 = -6x + 8y - 14 1 (6x - 2) 4 Solution: 1 (6x - 2) = 1·6x - 1·(-2) = 1 · 6·x + 1 · (-2) = 3 x - 1 4 4 4 4 1 4 1 2 2

Example from homework: Choose the property illustrated by the following statement. 2+ 𝑥+5 = 2+𝑥 +5 Associative property of addition Commutative property of addition Distributive property Identity element of addition Answer: A

More examples: Use the distributive property to write each sum as a product. 4x + 4y Solution: 4x + 4y = 4(x + y) (-1)·5 + (-1)·x Solution: (-1)· 5 + (-1) · x = (-1)(5 + x) or -(5 + x)

REMINDERS: HW 1.2/1.8 AND Gateway HW # 2 (with worksheet!) are due at the start of the next class session. You should also take the Practice Gateway Quiz at least once before the next class session.

and begin working on the homework assignment. You may now OPEN your LAPTOPS and begin working on the homework assignment.