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Source: — Data Sufficiency |
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by Bill@VeritasPrep » Tue May 01, 2012 6:42 pm
1) n(n+2) = 15

If n=3, n+2=5. 3*5 = 15. If n=-5, n+2=-3. -3*-5 = 15. Insufficient

2) (n+2)^n = 125

125=5^3, which means that n=3. (3+2)^3=5^3=125. Sufficient
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by Anurag@Gurome » Tue May 01, 2012 10:43 pm
amp0201 wrote:Q. What is the value of the integer n? (1) n(n + 2) = 15 (2) (n + 2)^n = 125
(1) n(n + 2) = 15
n² + 2n = 15
n² + 2n - 15 = 0
n² + 5n - 3n - 15 = 0
n(n + 5) - 3(n + 5) = 0
(n - 3)(n + 5) = 0
n = 3, -5
Two integer values of n, no definite answer; NOT sufficient.

(2) (n + 2)^n = 125
(n + 2)^n = 5^3
n = 3; SUFFICIENT.

The correct answer is B.
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