number property, new

[tanviet]

what is value of integer n

1, n(n+2)= 15

2, power n of (n+2) = 125

pls,help with this

[bluementor]

n is an integer.

Statement 1:

n(n+2) =15

we can have two possibilites for n: n = -5 and n = 3. Insufficient.

Statement 2:

(n+2)^n = 125

the only possible value for n is 3. Sufficient.

Choose B.

-BM-

[tanviet]

why do you know there is only 3 for the second case

[bluementor]

why do you know there is only 3 for the second case

because there only two possibilites to represent 125 in the form of x^n (with n being an integer)

125^1
5^3

Since n=1 does not satisfy statement 2, n cannot be 1. However n=3 satisfies statement 2.

hth.

-BM-