GOAL

1. 2.3 Subtraction of Real Numbers SUBTRACTING REAL NUMBERS 1 GOAL add opposite Example: EXAMPLE 1 EXAMPLE 2 To subtract a real number, ____ its ________. Rewrite by adding the opposite: Add:

2. a. –6 – 3 b. c. –15 – (–6) Extra Example 2 Simplify the expression: 10 – 5 + 14 – (–18). EXAMPLE 3 Extra Example 1 See page 781 for review on adding fractions.

3. EXAMPLE 4 Extra Example 3 Find the terms of 3x – 5. First, rewrite the expression as addition: The terms are 3x and –5.

4. Input Function Output 0 1 Extra Example 4 Evaluate the function y = –x – 7 for these values of x: –2, –1, 0, and 1. Organize your results in a table and describe the pattern. Pattern: Each time x increases by 1, y decreases by 1.

5. Checkpoint 1. Evaluate the expression: –5 – (–3) + 4 – 1. 2. Find the terms of –7 – (–2x ). 3. Evaluate the function y = 1 – x for these values of x: –2, –1, 0, and 1. Organize your results in a table and describe the pattern. 1 –7 and 2x As x increases by 1, y decreases by 1.

6. 2.3 Subtraction of Real Numbers 2 USING SUBTRACTION IN REAL LIFE GOAL EXAMPLE 5 EXAMPLE 6 In reporting gains or losses, it is common practice to use a plus sign(+) to indicate a gain and a minus sign (–) to indicate a loss. Note their use in examples 5 and 6.

7. The daily closing prices of a utilities stock for one week are given below. a) Find the change in the closing price from day to day. b) Write the changes you found in order. c) Find the difference of the greatest number and the least number. b. c. 122.76 – 121.42 = +1.34 123.51 – 122.76 = +0.75 121.19 – 123.51 = –2.32 117.06 – 121.19 = –4.13 Extra Example 5 and 6

8. 1. The daily closing prices of a software company’s stock for one week are given below. a)Find the change in the closing price from day to day b) Write the changes in order. c) Find the difference of the greatest number and the least number. Checkpoint –5.7, –3.9, –2.1, 1.5 7.2 a. –5.7 +1.5 –2.1 –3.9

9. QUESTIONS?