Integers: Addition and Subtraction

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Questions and Answers

What is the result of the expression $-8 - (-5) + 2 \times (-3)$?

  • -7
  • -1
  • 1
  • -9 (correct)

The expression $-5 \times (2 + (-2))$ results in a positive number.

False (B)

What integer, when added to -12, results in 5?

17

According to the order of operations, in the expression $3 + 4 \times 2$, the ________ operation should be performed first.

<p>multiplication</p> Signup and view all the answers

Match the integer operation with its corresponding property:

<p>$a + b = b + a$ = Commutative Property of Addition $a \times (b + c) = (a \times b) + (a \times c)$ = Distributive Property $a + 0 = a$ = Additive Identity Property $(a \times b) \times c = a \times (b \times c)$ = Associative Property of Multiplication</p> Signup and view all the answers

What is the quotient of $-48 \div (-6)$?

<p>8 (C)</p> Signup and view all the answers

Subtracting a negative integer from another integer always results in a smaller value than the original integer.

<p>False (B)</p> Signup and view all the answers

What is the additive inverse of -15?

<p>15</p> Signup and view all the answers

The product of a negative integer and a positive integer is always a ________ integer.

<p>negative</p> Signup and view all the answers

Which property is demonstrated by the equation $(3 + (-2)) + 5 = 3 + (-2 + 5)$?

<p>Associative Property of Addition (D)</p> Signup and view all the answers

Flashcards

What are integers?

Whole numbers that can be positive, negative, or zero.

Adding integers with the same sign

Add their absolute values and keep the common sign.

Adding integers with different signs

Find the difference between their absolute values and use the sign of the larger absolute value.

What is an additive inverse?

The opposite of a number; when added to the original number, the sum is zero.

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Subtracting an integer

Adding its additive inverse.

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Positive × Positive

Positive.

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Negative × Negative

Positive.

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Positive × Negative

Negative.

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What is the order of operations?

PEMDAS/BODMAS: Parentheses/Brackets, Exponents/Orders, Multiplication and Division, Addition and Subtraction

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Commutative Property

The order in which numbers can be added or multiplied without changing the result.

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Study Notes

Integers

  • Integers include positive whole numbers, negative whole numbers, and zero
  • Positive integers are greater than zero such as 1, 2, 3, etc.
  • Negative integers are less than zero such as -1, -2, -3, etc.
  • Zero is neither positive nor negative

Addition of Integers

  • Adding integers combines their values
  • To add integers sharing the same sign:
    • Add their absolute values together
    • Retain the sign they have in common
    • Example: (+3) + (+5) = +8
    • Example: (-2) + (-4) = -6
  • To add integers with different signs:
    • Find the difference between their absolute values
    • Use the sign of the integer with the greater absolute value
    • Example: (+7) + (-3) = +4 because |+7| > |-3|
    • Example: (-9) + (+2) = -7 because |-9| > |+2|
  • The additive inverse, or opposite, of integer 'a' is '-a,' and their sum equals zero: a + (-a) = 0
    • Example: 5 + (-5) = 0

Subtraction of Integers

  • Subtracting an integer equals adding its additive inverse
  • To subtract integer 'b' from integer 'a,' change 'b' to '-b' and add it to 'a': a - b = a + (-b)
    • Example: (+5) - (+2) = (+5) + (-2) = +3
    • Example: (+3) - (-4) = (+3) + (+4) = +7
    • Example: (-6) - (+1) = (-6) + (-1) = -7
    • Example: (-2) - (-5) = (-2) + (+5) = +3

Multiplication of Integers

  • When multiplying integers, resulting sign depends on the signs of the integers
    • Positive × Positive = Positive
      • Example: (+3) × (+4) = +12
    • Negative × Negative = Positive
      • Example: (-2) × (-5) = +10
    • Positive × Negative = Negative
      • Example: (+6) × (-1) = -6
    • Negative × Positive = Negative
      • Example: (-4) × (+3) = -12
  • If the signs are the same, the product is positive
  • If the signs are different, the product is negative

Division of Integers

  • Division rules mirror those of multiplication regarding the sign
    • Positive ÷ Positive = Positive
      • Example: (+10) ÷ (+2) = +5
    • Negative ÷ Negative = Positive
      • Example: (-8) ÷ (-4) = +2
    • Positive ÷ Negative = Negative
      • Example: (+15) ÷ (-3) = -5
    • Negative ÷ Positive = Negative
      • Example: (-20) ÷ (+5) = -4
  • Same signs yield a positive quotient
  • Different signs yield a negative quotient
  • Division by zero is undefined

Order of Operations

  • With expressions involving multiple operations, follow the order of operations (PEMDAS/BODMAS)
    • Parentheses/Brackets
    • Exponents/Orders
    • Multiplication and Division (left to right)
    • Addition and Subtraction (left to right)
  • Example: 2 + 3 × (-4)
    • First, multiplication: 3 × (-4) = -12
    • Then, addition: 2 + (-12) = -10
  • Example: (5 - 7) ÷ (-2) + 1
    • First, simplify parentheses: (5 - 7) = -2
    • Then, division: (-2) ÷ (-2) = +1
    • Finally, addition: 1 + 1 = 2

Properties of Integer Operations

  • Commutative Property: Applies to addition and multiplication
    • a + b = b + a
      • Example: 2 + (-3) = -3 + 2
    • a × b = b × a
      • Example: (-4) × 5 = 5 × (-4)
  • Associative Property: Applies to addition and multiplication
    • (a + b) + c = a + (b + c)
      • Example: (1 + (-2)) + 3 = 1 + (-2 + 3)
    • (a × b) × c = a × (b × c)
      • Example: ((-1) × 2) × 3 = (-1) × (2 × 3)
  • Distributive Property:
    • a × (b + c) = (a × b) + (a × c)
      • Example: 2 × (3 + (-4)) = (2 × 3) + (2 × (-4))
  • Identity Property:
    • Additive Identity: a + 0 = a
      • Example: -5 + 0 = -5
    • Multiplicative Identity: a × 1 = a
      • Example: 7 × 1 = 7

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