If b is greater than 1, which of the following must be negative?
A. (2 - b)(b - 1)
B. (b - 1)/3b
C. (1 - b)^2
D. (2 - b)/(1 - b)
E. (1 - b^2)/b
[spoiler]OA=E[/spoiler].
How can I discard the rest of the options? Experts, can you give me some help? <i class="em em-pray"></i>
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If b is greater than 1, which of the following must
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Gmat_mission
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mbawisdom
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Lets look at each answer:Gmat_mission wrote:If b is greater than 1, which of the following must be negative?
A. (2 - b)(b - 1)
B. (b - 1)/3b
C. (1 - b)^2
D. (2 - b)/(1 - b)
E. (1 - b^2)/b
[spoiler]OA=E[/spoiler].
How can I discard the rest of the options? Experts, can you give me some help? <i class="em em-pray"></i>
A. (2 - b)(b - 1): (+ or -)(+) --> answer can be + or -
B. (b - 1)/3b: (+)/(+) --> answer is +
C. (1 - b)^2 : square is never negative
D. (2 - b)/(1 - b): (+ or -)/(-) --> answer can be + or -
E. (1 - b^2)/b (-)/(+) --> answer is always negative as b^2 > 1!
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[email protected]
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Hi Gmat_mission,
We're told that B is greater than 1. We're asked which of the following MUST be negative (which really means "which of the following is ALWAYS NEGATIVE no matter how many different examples we can come up with"). This question can be solved by TESTing VALUES.
IF... B=2, then
Answer A = 0/1 = 0
Answer B = 1/6
Answer C = (-1)^2 = 1
Answer D = 0/-1 = 0
None of the first 4 answers is negative - and there's only one answer left...
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
We're told that B is greater than 1. We're asked which of the following MUST be negative (which really means "which of the following is ALWAYS NEGATIVE no matter how many different examples we can come up with"). This question can be solved by TESTing VALUES.
IF... B=2, then
Answer A = 0/1 = 0
Answer B = 1/6
Answer C = (-1)^2 = 1
Answer D = 0/-1 = 0
None of the first 4 answers is negative - and there's only one answer left...
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
GMAT/MBA Expert
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Jeff@TargetTestPrep
- GMAT Instructor
- Posts: 1462
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Since b is greater than 1, (1 - b^2) will always be negative, and thus (1 - b^2)/b will always be negative.Gmat_mission wrote:If b is greater than 1, which of the following must be negative?
A. (2 - b)(b - 1)
B. (b - 1)/3b
C. (1 - b)^2
D. (2 - b)/(1 - b)
E. (1 - b^2)/b
Answer: E
Jeffrey Miller
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