1. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers 1-2 Adding and Subtracting Real Numbers Holt Algebra 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Lesson Quiz Lesson Quiz

2. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Add real numbers. Subtract real numbers. Objectives

3. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers All the numbers on a number line are called real numbers. You can use a number line to model addition and subtraction of real numbers. Addition To model addition of a positive number, move right. To model addition of a negative number move left. Subtraction To model subtraction of a positive number, move left. To model subtraction of a negative number move right.

4. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Example 1A: Adding and Subtracting Numbers on a Number line Add or subtract using a number line. 1110 98 7 654321 0 –4 + (–7)

5. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Example 1B: Adding and Subtracting Numbers on a Number line Add or subtract using a number line. -3-20123456 7 89 3 – (–6)

6. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers The absolute value of a number is the distance from zero on a number line. The absolute value of 5 is written as |5|. 5 units 2101 234 56 6543 -- - -- - |5| = 5|–5| = 5

7. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers

8. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Example 2A: Adding Real Numbers Add.

9. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Example 2B: Adding Real Numbers Add. y + (–2) for y = –6

10. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Two numbers are opposites if their sum is 0. A number and its opposite are on opposite sides of zero on a number line, but are the same distance from zero. They have the same absolute value.

11. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers A number and its opposite are additive inverses. To subtract signed numbers, you can use additive inverses. 11 – 6 = 5 11 + (–6) = 5 Additive inverses Subtracting 6 is the same as adding the inverse of 6. Subtracting a number is the same as adding the opposite of the number.

12. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers

13. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Subtract. –6.7 – 4.1 Example 3A: Subtracting Real Numbers

14. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Subtract. 5 – ( – 4) Example 3B: Subtracting Real Numbers

15. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Subtract. Example 3C: Subtracting Real Numbers

16. Holt Algebra 1 1-2 Adding and Subtracting Real Numbers Example 4: Oceanography Application An iceberg extends 75 feet above the sea. The bottom of the iceberg is at an elevation of –247 feet. What is the height of the iceberg? Find the difference in the elevations of the top of the iceberg and the bottom of the iceberg.