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06 Feb 2018, 06:04
Kudos
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
80% (00:50) correct
20%
(00:29)
wrong
based on 57
sessions
History
Date
Time
Result
Not Attempted Yet
What is the value of a^4 - b^4 ?
(1) a^2 + b^2 = 24
(2) a^2 - b^2 = 0
(1) a^2 + b^2 = 24
(2) a^2 - b^2 = 0
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
06 Feb 2018, 06:21
Kudos
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Bunuel
As this looks like a very technical question, we'll try working with the equations.
This is a Precise approach.
(1) It isn't entirely clear how to transform a^2 + b^2 into a^4 - b^4 so simplification won't help.
Instead, we'll try numbers:
If a = 0 then b = \(\sqrt{24}\) and if b = 0 then a = \(\sqrt{24}\).
These give two different solutions, so it is insufficient!
(2) Since a^2 = b^2, then a^4 = b^4. Therefore a^4 - b^4 = 0.
Sufficient!
(B) is our answer.
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