Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 2.3 Subtracting Integers

Martin-Gay, Prealgebra & Introductory Algebra, 3ed 22 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. To subtract integers, rewrite the subtraction problem as an addition problem. Study the examples below. 9 5 = (–5) = 4 equal 4, we can say 9 5 = 9 + (–5) = 4 Since both expressions Subtracting Integers

Martin-Gay, Prealgebra & Introductory Algebra, 3ed 33 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 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.

Martin-Gay, Prealgebra & Introductory Algebra, 3ed 44 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 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 Subtracting Two Numbers

Martin-Gay, Prealgebra & Introductory Algebra, 3ed 55 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 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) ( – 5) Adding and Subtracting Integers

Martin-Gay, Prealgebra & Introductory Algebra, 3ed 66 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Evaluate x – y for x = – 6 and y = 8. x – y Replace x with – 6 and y with 8 in x – y. = ( ) – ( ) –6–6 8 = –1 4 = ( ) + ( ) –6–6 – 8 Evaluating Algebraic Expressions