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Source: — Data Sufficiency |
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by GMATGuruNY » Tue Jan 07, 2014 12:27 pm
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by sanju09 » Tue Jan 07, 2014 11:36 pm
buoyant wrote:Is a positive?

(1) x^2−2x+a is positive for all x

(2) ax^2+1 is positive for all x

[spoiler]OA:A[/spoiler]
(1) If x^2-2x+a is positive for all x, then it must be positive at x = 0 too, which directly announces that YES, a is positive. Hence Sufficient

(2) All non-negative values of 'a' satisfy this statement. Quite a few negative fractions 'a' also satisfy this statement. [spoiler]Hence, insufficient[/spoiler]


[spoiler]A[/spoiler]
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