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Re: If a and b are constants, what is the value of a ?
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26 Jul 2017, 13:15
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Top Contributor
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carcass wrote:
If a and b are constants, what is the value of a ?
1. a < b
2. (t − a)( t − b) = t² + t − 12, for all values of t.
Target question:What is the value of a?
Statement 1:a < b Definitely NOT SUFFICIENT
Statement 2: (t − a)( t − b) = t² + t − 12 Factor: t² + t − 12 = (t + 4)(t - 3) Rewrite in terms of (t - a) and (t - b) to get: t² + t − 12 = (t - -4)(t - 3) There are two possible cases: Case a: a = -4 and b = 3, in which case a = -4 Case b: a = 3 and b = -4, in which case a = 3 Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined Statement 2 tells us that EITHER a = -4 and b = 3 OR a = 3 and b = -4 Statement 2 tells us that a < b, which means it MUST be the case that a = -4 and b = 3 So, a = -4 Since we can answer the target question with certainty, the combined statements are SUFFICIENT
If a and b are constants, what is the value of a ?
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26 Oct 2018, 10:03
Isn't it possible for a=-6 and b=2?
(t-a)(t-b) = (t--6)(t-2) = t^2 + 6t - 2t -12 = t^2+4t -12. This solution appears to be consistent with the given constraints, and since it says a and b are "constants" the answer would be E.
Am i missing something?
gmatclubot
If a and b are constants, what is the value of a ?
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26 Oct 2018, 10:03
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67% (01:27) correct 
