Ch.1, Sec 5&6: Adding Subtracting Integers
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This document provides rules and examples for adding and subtracting integers: - When adding integers with the same sign, the sum is positive if both numbers are positive and negative if both are negative. - When adding integers with different signs, find the difference of the absolute values and the sign is that of the integer with the greater absolute value. - The sum of an integer and its opposite is zero. - To subtract integers, turn the subtraction into addition by changing the operation to addition and changing the sign of the second number. Some example problems are worked through to demonstrate applying these rules for adding and subtracting integers.
Ch.1, Sec 5&6: Adding Subtracting Integers
- 1. Chapter 1 Section 5: Adding Integers Section 6: Subtracting Integers By Ms. Dewey-Hoffman, 2009 http://msdhpowerpoints.blogspot.com/
- 2. Rules for Adding Integers Adding Integers with the Same Sign: The sum of two positive integers is positive. The sum of two negative integers is negative. Example: -12 + (-31) = -43 Example: 22 + 16 = 28 Adding Integers with Different Signs: Find the difference (subtraction) of their absolute values . The answer has the sign of the integer with the greater absolute value. Example: -125 + 35 = |-125| + |35| = 125 – 35 = 90 Biggest number is negative, so the answer is negative. -90
- 3. Addition of Opposites It’s a property! The sum of an integer and it’s opposite is zero. Example: 7 + -7 = 0 Adding Integers Turn it into a word problem and say it out loud. Example: -1 + 4, You owe me 1 dollar, you have 4 to pay me back, how much do you have left over? 3. Example: 7 + (-3), You have 7 dollars, you buy something for 3 dollars, how much do you have left? 4. You give up negative numbers and you keep positive numbers. Example Problems : -2 + (-2) = 2 + (-6) = -4 + 9 = -5 + (-1) = Adding Integers
- 4. Adding Integers with Different Signs: Example Problems Remember: Find the difference of their absolute value. The sign of the number with the greatest absolute value gives the sign of the answer. Also: Go left to right when all you’re doing is adding and subtracting! 1 + (-3) + 2 + (-10) = -250 + 200 + (-100) + 220 = The elevation of a monitor in Pinon Flat, California, is 1,696 meters higher than the monitor in Hockley, Texas (at -416 meters). Find the elevation of the monitor in Pinon Flat. Write an expression. Solve.
- 5. Subtracting Integers Add Its Opposite Turn the subtraction sign into addition and take the OPPOSITE of the second number. Then treat the problem as an addition problem. (Difference of absolute value, etc). Example Problems: 2 – 5 = 44 – 100 = 32 – (-3) = -40 – 66 = 2 – 48 = The lowest temperature ever recorded in Antarctica was -89°C. The lowest temperature ever recorded on the moon was about -170°C. What is the difference in the temperatures?
- 6. Assignment #3 Pages 26-27: 21-32 all, 54-60 even. Pages 31-32: 20-36 even, 57-61 all. No extra credit today. Remember to show work, set up your page correctly and box your answers! Due September 4 th , 2009.