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If (a1)(b2) =0, which of the following must be true ? [#permalink]
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21 Mar 2012, 14:52
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If (a1)(b2) =0, which of the following must be true ? I. a=1 and b=2 II. if a is not = 1, then b=2 III. if a=1, then b is not=2 A. I only B. II only C. III only D. I and II E. II and III
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Last edited by Bunuel on 21 Mar 2012, 15:02, edited 1 time in total.
Edited the question



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Re: PT #13 PS 4 Q 16 [#permalink]
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21 Mar 2012, 14:57
You need to edit the question sir..
should be:
(a1)(b2)=0
The only thing you can say for sure is either a = 1 or b = 2 or both
So the answer is b)
If A doesnt equal 1, then b must equal 2



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Re: PT #13 PS 4 Q 16 [#permalink]
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21 Mar 2012, 15:01
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eybrj2 wrote: If (a  1) (b  1) = 0, which of the following must be true?
1. a = 1 and b = 2
2. If a is not 1, then b = 2
3. If a =1, then b is not 2.
a) 1 only
b) 2 only
c) 3 only
d) 1 and 2
e) 2 and 3 QUESTION SHOULD READ: If (a1)(b2) =0, which of the following must be true ? I. a=1 and b=2 II. if a is not = 1, then b=2 III. if a=1, then b is not=2 A. I only B. II only C. III only D. I and II E. II and III \((a1)(b2) =0\) > either \(a=1\) or \(b=2\) (or both). I. a=1 and b=2 > not necessarily true: for example if a=1 then b can be any number II. if a is not = 1, then b=2 > if \(a\neq{1}\) then in order \((a1)(b2) =0\) to hold true then \(b=2\) MUST be true; III. if a=1, then b is not=2 > not necessarily true: \(a=1\) and \(b=2\) can be simultaneously true. Answer: B.
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Re: If (a1)(b2) =0, which of the following must be true ? [#permalink]
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23 Mar 2012, 04:26
B. II only
I is not necessarily true as it makes both (a1) and (b2) equal zero which is not necessarily true. if either one of these were equal to zero it would satisfy the equation
II must be true. If a is not = 1 the (a1)#0 there (b2) must be equal to zero and b =2
III not necessarily true. It may be the case that a=1 and b=2 as this would lead to 0x0=0 which satisfies the equation.



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Re: If (a1)(b2) =0, which of the following must be true ? [#permalink]
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03 Aug 2014, 20:43
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Re: If (a1)(b2) =0, which of the following must be true ? [#permalink]
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03 Aug 2014, 21:30
(a1)(b2)=0 so either a=1 or b=2 or both. It 'or' not 'and', so it could be any of the three possibilities. so I and III cannot be always true.
so the answer is B, II only.



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Re: If (a1)(b2) =0, which of the following must be true ? [#permalink]
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03 Aug 2014, 21:48
if (a1)(b2) =0 then one of the following have to be true:
1. a = 1, and b can be any number 2. b = 2, and a can be any number 3. both and a = 1, b = 2
hope this helps



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Re: If (a1)(b2) =0, which of the following must be true ? [#permalink]
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13 Nov 2015, 06:22
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Re: If (a1)(b2) =0, which of the following must be true ? [#permalink]
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23 Nov 2016, 06:45
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Re: If (a1)(b2) =0, which of the following must be true ?
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