Please explain - thanks

[tvtt2010]

k#0, 1, and -1. is 1/k>0
1. 1/(k-1)>0
2. 1/(k+1)>0

[AVbyT]

Statement 1: For 1/(k-1)>0, k>1 => 1/k > 0. Hence, Sufficient

Statement2: For 1/(k+1)> 0, k > 0 OR 0 > k > -1.
For, k > 0 => 1/k > 0
BUT, for 0>k>-1, say k = -0.5, 1/k < 0

Hence, Insufficient

My Answer:A

[arashyazdiha]

the question means that is K>0?
1)if K>1
2)if K>-1

1)alone this is sufficient
2) it might be >0 or <0 so insufficient

I'll go with A

[GmatKiss]

k#0, 1, and -1. is 1/k>0
1. 1/(k-1)>0
2. 1/(k+1)>0

FROM 1 and given,
K cannot be -1,0,1
K cannnot be -2 (1/-3 is not greater than 0)
K has to be +ve number > 1, Hence sufficient!

FROM 2 and given,
K cannot be -1,0,1
K cannnot be -2 (1/-1 is not greater than 0)
K has to be +ve number > 1, Hence sufficient!

IMO:D

[arashyazdiha]

Hi GmatKiss,
But the thing is that there is no indication in the question stem that k has to be an integer.
Did you assume the same thing?

[GmatKiss]

oh yes!! thanks arashyazdiha =for correcting

[zeynep]

I think A is right since you can prove B is insifficent when you think k=2/5 and 1/(1+2/5)=1/ (7/5) which is 5/7 less than 1.

this is one of case ans similarly you can prove the case that can be greater than 1 as well!