9514 1404 393
Answer:
a. -7, -7
b. -14, 2
c. -14, -14
d. 1, -1
e. misuse of the associative property leads to different results
Step-by-step explanation:
Your calculator (or a spreadsheet) can figure these easily.
a. -12 +(-4 +9) = 12 +5 = -7
(-12 +(-4)) +9 = -16 +9 = -7
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b. (14 -20) -8 = -6 -8 = -14
14 -(20 -8) = 14 -12 = 2
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c. (14 +(-20)) +(-8) = -6 -8 = -14
14 +(-20 +(-8)) = 14 +(-28) = -14
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d. -1 -(-1 +(-1)) = -1 -(-2) = -1 +2 = 1
(-1 -(-1)) +(-1) = (-1+1) -1 = 0 -1 = -1
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e. The associative property works for addition. When the associative property is used to rearrange subtraction problems, the minus signs need to be kept with the numbers, as in (c). That is, the problem needs to be expressed as a sum of signed numbers.
In (d), the term -(-1 +(-1)) was broken in the middle when the sum was rearranged for the second expression. Only terms in the same level of parentheses can be rearranged by the associative property.
