Value of K

[fighting_cax]

see attached image[/img]

[Brent@GMATPrepNow]

The question "Is 1/k > 0" can be rewritten as "is k positive?" since the only way for 1/k to be greater than 0 is for k to be positive.

(1) If 1/(k-1) is positive, then k-1 is positive: 0<k-1
Add 1 to both sides: 1<k
k is definitely positive
SUFF

(2) If 1/(k+1) is positive, then k+1 is positive: 0<k+1
Subtract 1 from both sides: -1<k
k can be either positive or negative.
INSUFF

The answer is A

[welcome]

same as Brent , I'll go for A. what is OA.

[x2suresh]

Agree with Brent A.

[fighting_cax]

Thanks Brent - your explanation is very clear.

[Uri]

(2) If 1/(k+1) is positive, then k+1 is positive: 0<k+1
Subtract 1 from both sides: -1<k
k can be either positive or negative.
INSUFF

The answer is A

From (2), we know that k>-1. And we are told explicitly that k is not 0, 1 or -1. Thus combining this two, k>1. Hence (2) should also be sufficient.

Please rectify me if I have made any mistake.

[rolrol19]

Agree with Uri!

[cramya]

From (2), we know that k>-1. And we are told explicitly that k is not 0, 1 or -1. Thus combining this two, k>1. Hence (2) should also be sufficient.

Please rectify me if I have made any mistake

Agree with Uri!

A common mistake is to assume k is an integer. The problem states k is not 0,1 or -1 so it can be anything else(integer or fraction)


Stmt II

1/k+1 > 0

k= - 1/2 still 1/k+1 > 0 and 1/k is not greater than 0



Hope this helps!

Regards,
CR

[Uri]

thanks, cramya! understood my mistake