Chapter 2: Solving One-Step Equations and Inequalities
2.1
Properties of Numbers
Properties
• Commutative property of addition & multiplication:– Changing the order of the values you are adding or
multiplying does not change the sum or product
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Properties
• Associative properties of addition & multiplication– Changing the grouping of the values you are adding
or multiplying does not change the sum or product
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Example 1
• Carlos rented a set of golf clubs for $7 and a golf cart for $12. He paid a greens fee of $23. Find his total cost.
Properties
• Identity properties of addition & multiplication– The sum of any number and zero is the original
number– The product of any number and 1 is the original
number
Example 2• Name each property shown:
• 5 · 7 = 7 · 5
• c · 1 = c
• 7 + a = a + 7
• 5(xy) = (5x)y
Example 3
• Use mental math to simplify:
(81 + 6) + 9
Example 4
• Suppose you buy the school supplies, a highlighter for $.85, an eraser for $.35, and paper for $1.65. Use mental math to find the cost of the supplies.
Example 5
• Use mental math to simplify:
(4 · 9) · 5
Example 6
• Use mental math to simplify:
5 · 9 · 6 · (-2) · (-1)
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