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Grade 9 Integer Review

Grade 9 Integer Review. Review Day 1. What is an Integer?. A whole number that is either greater than 0 (positive) or less than 0 (negative) Can be visualized on a number line:. What are Opposites?. Two integers the same distance from the origin, but on different sides of zero

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Grade 9 Integer Review

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  1. Grade 9 Integer Review Review Day 1

  2. What is an Integer? • A whole number that is either greater than 0 (positive)or less than 0 (negative) • Can be visualized on a number line:

  3. What are Opposites? • Two integers the same distance from the origin, but on different sides of zero • Every positive integer has a negative integer an equal distance from the origin • Example: The opposite of 6 is -6 • Example: The opposite of -2 is 2

  4. What is Absolute Value? • Distance a number is from zero on a number line (always a positive number) • Indicated by two vertical lines | | • Every number has an absolute value • Opposites have the same absolute values since they are the same distance from zero • Example: |-8| = 8 and |8| = 8 • Example: |50| = 50 and |-50| = 50

  5. What Can We Do to Integers? • Integers are numbers, so we can add, subtract, multiply, and divide them • Each operation has different rules to follow

  6. First Remove Double Signs!! Eg: (-3) + (-4)

  7. Adding Rules – Same Signs • If the integers have the SAME signs: ADD the numbers & keep the same sign! • Positive + Positive = Positive Answer • Negative + Negative = Negative Answer

  8. Adding (Same Signs) - Examples #1. -3 + (-10) - Change the double sign + (-) to a (-) - Same signs - add and keep sign! = -13 #2. 6 + (8) - Same sign so add and keep sign! = 14

  9. Adding Rules – Different Signs • If the integers have DIFFERENT signs: SUBTRACT the numbers & use sign of the BIGGER( further from zero)number! • Bigger # is Positive = Positive Answer • Bigger # is Negative = Negative Answer

  10. Adding (Different Signs) - Examples #1. -13 + (7) - Subtract the numbers - Keep the sign of the number furthest from zero (bigger number) = -6 #2. 23 + (-8) - Subtract the numbers - Keep the sign of the number furthest from zero (bigger number) = +15

  11. Subtracting Rules • Make sure to change any double signs • Follow the rules forADDITION: • -SAME signs: Add & keep the same sign -DIFFERENT signs: Subtract & use sign of bigger #

  12. Subtracting - Examples • #1. -5 – -12 • - Change double signs to a + • - Subtract the two numbers and keep the sign of the number further from zero (bigger number) • = +7 • #2. 9 – 23 • - Subtract the two numbers and keep the sign of the number further from zero (bigger number) • = -14 • d

  13. Multiplying Rules • Multiply the numbers like usual • If the integers have the SAMEsigns: ANSWERwill be POSITIVE • If the integers have DIFFERENTsigns: ANSWERwill be NEGATIVE

  14. Multiplying - Examples • #1. -3 · (-5) • - negative times negative = + • = +15 • #2.-9 · (+10) • - Negative times a positive = (-)

  15. Dividing Rules • Divide the numbers like usual • If the integers have the SAMEsigns: ANSWERwill be POSITIVE • If the integers have DIFFERENTsigns: ANSWERwill be NEGATIVE

  16. Dividing - Examples • #1. -33 ÷ (-3) • - Negative divide negative = + • = +11 • #2.-90 ÷ (+10) • - Negative divide a positive = (-) • = -9

  17. Mixed Practice Solve the following problems: -9 + - 9 -18 7 × -4 -28 -10 - (-19) 9 -35 ÷ -7 5 15 + -25 -10 -23 - 9 -32

  18. Review • Visit the website below for additional information on integers: • http://www.math.com/school/subject1/ lessons/S1U1L10GL.html

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