2. Subtracting Integers Section 2.3

3. To subtract integers, rewrite the subtraction problem as an addition problem. Study the examples below. 9 5 = 4 9 + (- 5) = 4 equal 4, we can say 9 5 = 9 + (- 5) = 4 Since both expressions 2 Martin-Gay, Prealgebra, 5ed

4. Subtracting Two Numbers If a and b are numbers, then a b = a + (-b). To subtract two numbers, add the first number to the opposite (called additive inverse) of the second number. 3 Martin-Gay, Prealgebra, 5ed

5. subtraction= first number + opposite of second number 7 – 4=7+(- 4)=3 - 5 – 3=- 5- 5+(- 3)=- 8- 8 3 – (- 6)=3+6=9 - 8 – (- 2)=- 8- 8+2=- 6- 6 4 Martin-Gay, Prealgebra, 5ed

6. Adding and Subtracting Integers If a problem involves adding or subtracting more than two integers, rewrite differences as sums and add. By applying the associative and commutative properties, add the numbers in any order. 9 - 3 + (-5) - (-7) = 9 + (-3) + (-5) + 7 6 + (-5) + 7 1 + 7 8 5 Martin-Gay, Prealgebra, 5ed

7. Evaluate x - y for x = - 6 and y = 8. Evaluating Algebraic Expressions x - y Replace x with - 6 and y with 8 in x - y. = ( ) - ( )- 68 = - 14 = ( ) + ( )- 6- 8 6 Martin-Gay, Prealgebra, 5ed