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Chapter 1Section 5: Adding IntegersSection 6: Subtracting IntegersBy Ms. Dewey-Hoffman, 2009 http://msdhpowerpoints.blogspot.com/
Page 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
Page 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
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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.
1) Write an expression.
2) Solve.
Page 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?
Page 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 4th, 2009.