1. SECTION 2.1 THE REAL NUMBERS AND ABSOLUTE VALUE Algebra I

2. Warm-up Evaluate each expression. 1.190 – 128 ÷ 4 2.21 – 6 · 3 + 4² 3.8 · 9 + 7 · 5 4.2(5 + 8 – 6) + 11 5.3² · 4 + [9 – (2² - 1)]

3. LanguageMath alphabetdigits wordsnumbers Nouns, Verbs, Adjectives Natural: 1, 2, 3, …. Whole: 0, 1, 2, 3, … Integers: … -3, -2, -1, 0, 1, 2, 3, … Rational numbers: Any number that can be expressed in the form a/b, where a and b are integers and b ≠ 0 Irrational numbers: Any number that can not be expressed in the form a/b, where a and b are integers and b ≠ 0 Real Number: Any number that is rational or irrational See Diagram p56 in book

4. LanguageMath alphabetdigits wordsnumbers Order using the alphabet Order using relational operators:, =, ≤, ≥, ≠ Example: Insert an ordering symbol to make each statement true. a.5 _____ - 7 b. 1/2 ____ 8/16 c. -4.8 ____ -4.7 d. 4 ⅔ _____ 6 Practice: Try this – top of page 57.

5. Opposites : any two numbers that lie on opposite sides of 0 and are the same distance from 0. 2 and -2 are opposites Example: a.-(-10)b. –(-3/5)c. -0d. –(8.6 – 1.5) Practice: Try this – Middle of page 57.

6. Definition of Absolute Value The absolute value a real number x is the distance from x to 0 on a number line. The symbol |x| means the absolute value of x Example: Simplify a. |-8|b. |16|c. |7 + 2| Practice: Try this – top of page 58 If time: Pg 58 Guided practice #4-15a Homework: Pg 58-59 Practice and Apply #16-60a