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4.3 Adding Integers using addition Rules. Objective: Students will be able to add negative and positive integers. Finding Absolute Values. The Absolute Value of a number is its distance from zero on the number line. The absolute value of 4 is written: 4. 4 is 4 units from zero.
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4.3 Adding Integers using addition Rules Objective: Students will be able to add negative and positive integers.
Finding Absolute Values The Absolute Value of a number is its distance from zero on the number line. The absolute value of 4 is written: 4 4 is 4 units from zero
Find the Absolute Values: • Find the absolute value of the number. • 5 b) -8 c) 0 d) ½ 5 = 5 -8 = 8 0 = 0 ½ =1/2 Read: The absolute value of 5 is 5
Add: 4 + 9 = -4 + -9 = -4 + 9 = 4 + -9 = When the integers have the same sign, add their absolute values. Use that sign on the sum! 13 -13 When the integers have different signs, subtract their absolute values. Use the sign of the integer with the greatest absolute value. 5 - 5 Signs are different so you have to subtract. Think: 9 - 4 5 This is the one time you will have to change the order of the problem: Always subtract the smaller absolute value from the greater absolute value!
Let’s Give it a Try: -11 + (-3) = 6 + (-7) = -3 + 8 = -6 + 15 + (-2) = - 14 Signs are the same: Add and keep the sign! - 1 Signs are different so subtract: THINK: 7-6 (subtract smaller absolute value number from greater absolute number) Remember 7 has greater absolute value so your sum will be _____________! Negative 5 Signs are different so subtract: THINK: 8-3 (subtract smaller absolute value number from greater absolute number) Remember 8 has greater absolute value so your sum will be ____________! Positive 7 Use the commutative and associative properties of addition to group numbers with the same signs. Add -6 + -2 = -8 (Keep the negative sign!) SO: -8 + 15 = Signs are different so Subtract: 15-8= Sign will be ____________! Positive
Remember: When the integers have the same sign—add and go with the sign! -8 + -10= -18 8 + 10= 18 5 When integers have different signs: subtract and keep the sign of the integer with the greatest absolute value! - 8 + 10 = 2 8 + -10 = -2 Think: 10 – 8 = 2
It’s that time again: Homework Page 179 Problems: 8-33 all Due Monday! Don’t try this at home!! This guy is crazy!