1. + 1.5 Adding and Subtracting Real Numbers Wednesday August 26, 2015

2. + Warm up Write an algebraic expression for each phrase. 1. A number n divided by 4 2. 2 less than the product of 5 and n. Simplify 3. 24 ÷ (3 + 2 2 ) 4. √144 Evaluate for the given values 5. 3x  2 ÷y : x=3 & y=6 6. (4a) 3 ÷(b-2) ; a=2 & b=4

3. + Adding and Subtracting Real Numbers Objective: I can find sum and differences of Real Numbers. Essential Understanding: You can add or subtract any real numbers using a number line model. You can also add or subtract real numbers using rules involving absolute value Purpose: To model a real-world situation by adding and subtracting real numbers Get Ready: Gift Card $50, buy new game $19, buy new jacket $29, Aunt Sue adds $25, buy new headphones $13, whats left over? How much do you need to add to keep balance at $25?

4. + Using number line models Draw a number line to model the given problems 1) 3 + 5 2) 3 + (-5) 3) -3 +5 4) -3 + (-5)

5. + Key Concepts Adding numbers with same signs, add their absolute values. Ex: 3 + 4 = 7 -3 + (-4) = -7 Adding numbers with different signs, subtract their absolute values. The sign will be that of the addend with the greater absolute value. Ex: -3 + 4 = 1 3 + (-4) = -1

6. + What is each sum? A. -12 + 7 =? 12 – 7 = 5 The difference of the absolute values = 5. = -5Since 12 is the larger addend, the answer will carry the negative sign. B. -18 + (-2) =? The addends have the same sign, so 18 + 2 = 20 add their absolute values and keep the sign. = -20

7. + Practice -16 + (-8) = -11 + 9 = 9 + (-11) = -6 + (-2) = -8 + 4 =

8. + Subtracting Real Numbers To subtract a real number, add its opposite : a – b = a +(-b) Ex: 3-5 = 3 +(-5) = -2 3 – (-5) = 3 + 5 = 8 What is each difference? -8 – (-13) = -8 + 13 The opposite of -13 is 13, so add 13 = 5 3.5 – 12.4 = 3.5 + (-12.4) The opposite of 12.4 is -12.4, so add - 12.4 = -8.9

9. + Practice 1. 4.8 – (-8.7) = 2. -12 + 9 = 3. -4 + (-3) = 4. -3 – (-5) = 5. 1.5 – 8.5 = On a number line, how is subtraction of a negative number related to addition of a positive number?