princessss wrote:If k is not equal to 0, 1, or -1, is 1/k>0?
(1) 1/(k-1)>0
(2) 1/(k+1)>0
My question is why B isn't correct.
If k is not 0,1 or -1 it can be 2,3 ... and it can be -2,-3 etc.
If we say that k is 2 than 1/(2+1) > 0 true
But, since it can't be -1 if k is negative the fraction can be >0. Doesn't that make B sufficient? K must be positive?
The correct answer is A.
Please help
In order for 1/k to be positive, k must be positive. Rewritten, the question is asking:
Is k>0?
Statement 1:
In order for 1/(k-1) to be positive, k-1 must be positive. Rewritten, statement 1 tells us:
k-1>0
k>1
Thus, k>0. Sufficient.
Statement 2:
In order for 1/(k+1) to be positive, k+1 must be positive. Rewritten, statement 2 tells us:
k+1>0
k>-1
Thus, k could be negative (k = -1/2, for example), or k could be positive (k = 2, for example). Insufficient.
The correct answer is
A.
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