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| Question 224100:  1 . Which of the following sets is not closed under addition?
 A. odd numbers
 B. real numbers
 C. whole numbers
 D. negative integers
 = i got A
 2 . Which property is illustrated in the following?
 5 + 6 + 7 = 6 + 5 + 7
 A. commutative
 B. associative
 C. reflexive
 D. transitive
 = i got A
 3 . Which property is illustrated in the following?
 4 + (3 + x) = (4 + 3) + x
 A. commutative
 B. reflexive
 C. associative
 D. transitive
 = i got C
 4 . Is subtraction of real numbers commutative?
 A. Yes
 B. No
 = i got B
 5 . When using a number line to simplify 3 + (–6), you start at which point on the number line?
 A. origin
 B. –6
 C. 3
 D. –3
 = i got A
 6 . Simplify (–4 + 6) – 2.
 A. 8
 B. 4
 C. –4
 D. 0
 = i got D
 7 . Simplify –9 + (–3t) + (–21).
 A. –12 + (–3t)
 B. –33t
 C. –30 + (–3t)
 D. 12 + (–3t)
 = i got B
 8 . Simplify [–7 + 3] + (–4 + (–2)).
 A. –2
 B. –10
 C. –6
 D. 2
 = i got B
 9 . Given x = –3, y = 6, and z = –4, evaluate –z + x – y.
 A. –7
 B. –13
 C. –5
 D. –1
 = i got C
 10 . Simplify x + 5 + [–(x) + (–14)].
 A. –9 + 2x
 B. 19
 C. –9 – x
 D. –9
 = i got A
 Is it all correct ?
 Thanks ! :)
 
 Found 2 solutions by  rapaljer, jim_thompson5910:
 Answer by rapaljer(4671)
      (Show Source): 
You can put this solution on YOUR website! I agree with all but 5, 7, and 10. 
 In #5, I may be wrong, but I would have started at 3.  However, it is correct that you have to begin at 0 in order to get to 3.  I'm not sure how your particular curriculum views this.
 
 I disagree with #7 and 10.  Is this a take home test???
 
 R^2
 
 Dr. Robert J. Rapalje
Answer by jim_thompson5910(35256)
      (Show Source): 
You can put this solution on YOUR website! # 1 Correct since odd + odd = even (eg: 3+5=8) 
 # 2 Correct
 
 # 3 Correct
 
 # 4 Correct (eg: 5-3 does not equal 3-5)
 
 # 5 Incorrect. This question was pretty tricky since you can start at either 3 or -6, but I think the book is looking for you to start with the first given number 3 and then move to the left 6 units (ie subtract 6 from 3). So the answer is C)
 
 # 6 Correct
 
 # 7 Incorrect. You can combine the terms -9 and -21 to get -30, but you CANNOT combine -30 and -3t to get -33t since they are NOT like terms. The only thing you can do is to leave them as they are and say that the answer is -30+(-3t) which means that the answer is C)
 
 # 8 Correct.
 
 # 9 Correct.
 
 # 10 Incorrect. Note how x + (-x) is the same as x - x which subtracts to 0x or just 0. This means that the 'x' terms just cancel out and go away. We're then left with 5 + (-14) = -9 which gives the answer D) -9
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