Is it B? From (1) we can gather that
n^2 + 2n -15 = 0
(n+5)(n-3) = 0
n = 3 or -5...not sufficient.
But using (2) if we factorize 125
125 = 5 * 25 = 5*5*5 = 5^3, so n=3.
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Finding "N"
Source: Beat The GMAT — Data Sufficiency |
with statement 1:
n(n+2)=15 This is a quadratic equation so expand it out
n^2 +2n -15 = 0
(n+5)(n-3)=0
n=-5, +3
n has 2 values so statement 1 is not sufficient
with statement 2:
(n+2)^n = 125
n = 3
statement 2 is sufficient but statement 1 is not...B
n(n+2)=15 This is a quadratic equation so expand it out
n^2 +2n -15 = 0
(n+5)(n-3)=0
n=-5, +3
n has 2 values so statement 1 is not sufficient
with statement 2:
(n+2)^n = 125
n = 3
statement 2 is sufficient but statement 1 is not...B
Phantom, I agree that 125 has roots 5, -5 and -5, but for other value of n (other than 3) is (n+2)^n = 125? I think the only possible value of n satisfying that equation is 3. hence I believe the answer to be B. Can you provide an eloborate explantion?
