Ch 1 Sec 4: Slide #1 Columbus State Community College Chapter 1 Section 4 Subtracting Integers

Ch 1 Sec 4: Slide #2 Subtracting Integers 1.Find the opposite of a signed number. 2.Subtract integers. 3.Combine adding and subtracting of integers.

Ch 1 Sec 4: Slide #3 Finding the Opposites of Signed Numbers EXAMPLE 1 Finding the Opposites of Signed Numbers Find the opposite (additive inverse) of each number. Show that the sum of the number and its opposite is 0. (a)9 (b) – 14 (c)0 The opposite of 9 is – 9and 9 + – 9 = 0 The opposite of – 14 is 14and – = 0 The opposite of 0 is 0and = 0

Ch 1 Sec 4: Slide #4 Subtracting Two Integers To subtract two numbers, add the first number to the opposite of the second number. Remember to change two things: Step 1Make a pencil stroke to change the subtraction symbol to an addition symbol. Step 2Make a second pencil stroke to change the second number to its opposite. If the second number is positive, change it to negative. If the second number is negative, change it to positive.

Ch 1 Sec 4: Slide #5 CAUTION When changing a subtraction problem to an addition problem, do not make any change in the first number. The pattern is 1 st number – 2 nd number = 1 st number + opposite of 2 nd number.

Ch 1 Sec 4: Slide #6 Subtracting Two Integers EXAMPLE 2 Subtracting Two Integers Make two pencil strokes to change each subtraction problem into an addition problem. Then find the sum. (a)9 – 15 – Change subtraction to addition – Change 15 to – 15 = – 6

Ch 1 Sec 4: Slide #7 Subtracting Two Integers EXAMPLE 2 Subtracting Two Integers Make two pencil strokes to change each subtraction problem into an addition problem. Then find the sum. (b) – 17 – – 8 Change subtraction to addition. + – 17 – 8 – Change – 8 to + 8 = – 9 +

Ch 1 Sec 4: Slide #8 Subtracting Two Integers EXAMPLE 2 Subtracting Two Integers Make two pencil strokes to change each subtraction problem into an addition problem. Then find the sum. (c)4 – – 12 Change subtraction to addition. 4 – – 12 Change – 12 to –

Ch 1 Sec 4: Slide #9 Subtracting Two Integers EXAMPLE 2 Subtracting Two Integers Make two pencil strokes to change each subtraction problem into an addition problem. Then find the sum. (d) – 3 – 6 Change subtraction to addition. – 3 – 6 Change 6 to – 6. – – 3 + – 6 –9–9

Ch 1 Sec 4: Slide #10 Change subtraction to addition. Change – 10 to 10. Change 2 to – 2. – – 7 + – 2 – 5 + – 10 + – Combining Addition and Subtraction EXAMPLE 3 Combining Addition and Subtraction Simplify by completing all the operations. – 5 – – 10 + – 7 – – 7 + – 2 – 2 + – 2 – 4

Ch 1 Sec 4: Slide #11 Calculator Tip – TI-30X IIS (–) Example 3: – 5 – – 10 + – 7 – 2 Calculator Tip You can use the negative sign key on your TI-30X IIS calculator to enter negative numbers. (–) – – 2= (–) –4–4

Ch 1 Sec 4: Slide #12 + – Calculator Tip – TI-30Xa Calculator Tip You can use the change of sign key on your TI-30Xa calculator to enter negative numbers. Example 3: – 5 – – 10 + – 7 – 2 + – –– 2= – –4–4

Ch 1 Sec 4: Slide #13 Subtracting Integers Chapter 1 Section 4 – End Written by John T. Wallace