1. Pre-Algebra 2-2 Subtracting Integers Pre-Algebra 5 for 5 for 5 Lesson Presentation Lesson Presentation

2. Pre-Algebra 2-2 Subtracting Integers 5 for 5 Copy and complete the magic square. The magic sum is 0. –8+3 –20 –3 +5 +2 –5+8

3. Pre-Algebra 2-2 Subtracting Integers Homework due Thursday Page: 26 -27 Problems: 3, 4, 5, 9, 10, 14, 16, 19, 22, 24, 30

4. Pre-Algebra 2-2 Subtracting Integers Essential Question : How do you subtract one integer from another?

5. Pre-Algebra 2-2 Subtracting Integers Adding Integers – Review Sign the same, add and keep sign Different signs, subtract and keep The sign of the highest absolute number. Properties of Addition Commutative Inverse Identity

6. Pre-Algebra 2-2 Subtracting Integers SUBTRACTING INTEGERS WordsNumbersAlgebra Change the subtraction sign to an addition sign and change the sign of the second number. 2 – 3 = 2 + (–3) 4 – (–5) = 4 + 5 a – b = a + (–b) a – (–b) = a + b

7. Pre-Algebra 2-2 Subtracting Integers Example 1ABC: Subtracting Integers A. –7 – 4 –7 – 4 = –7 + (–4) B. 8 – (–5) 8 – (–5) = 8 + 5 C. –6 – (–3) –6 – (–3) = –6 + 3 = –11 = 13 = –3 Add the opposite of 4. Add the opposite of –5. Add the opposite of –3. Same sign; use the sign of the integers. 6 > 3; use the sign of 6. Subtract.

8. Pre-Algebra 2-2 Subtracting Integers A. 8 – j for j = –6 8 – j 8 – (–6)Substitute –6 for j. Evaluate the expression for the given value of the variable. = 8 + 6 = 14 Add the opposite of –6. Same sign; use the sign of the integers. Example 2A: Evaluating Expressions with Integers

9. Pre-Algebra 2-2 Subtracting Integers B. –9 – y for y = –4 = –9 + 4 = –5 Evaluate the expression for the given value of the variable. –9 – y –9 – (–4)Substitute –4 for y. Add the opposite of –4. 9 > 4; use the sign of 9. Example 2B: Evaluating Expressions with Integers

10. Pre-Algebra 2-2 Subtracting Integers C. n – 6 for n = –2 n – 6 –2 – 6Substitute –2 for n. Evaluate each expression for the given value of the variable. = –2 + (–6) = –8 Add the opposite of 6. Same sign; use the sign of the integers. Example 2C: Evaluating Expressions with Integers

11. Pre-Algebra 2-2 Subtracting Integers The top of the Sears Tower in Chicago, is 1454 feet above street level, while the lowest level is 43 feet below street level. How far is it from the lowest level to the top? Additional Example 3: Word Problem 1454 – (–43) Subtract the lowest level from the height. 1454 + 43 Add the opposite of ( – 43). = 1497 Same sign; use the sign of the integers. It is 1497 feet from the lowest level to the top.