gmatprep k does not = -1,0,1, is (1/k) > 0?
1. 1/(k-1)>0
2. 1/(k+1)>0
The answer is A. I am getting D. Can someone please help with this problem. Thanks in advance.
gmatprep k does not = -1,0,1, is (1/k) > 0?
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1. 1/(k-1) > 0
Then k - 1 > 0
k >1
Then 1/k > 0.
Sufficient.
2. 1/(k+1)>0
k+1>0
k>-1
Choose k = -1/2, then 1/k = -2.
Choose k = 1/2, then 1/k = 2.
Insufficient.
Answer is A.
Then k - 1 > 0
k >1
Then 1/k > 0.
Sufficient.
2. 1/(k+1)>0
k+1>0
k>-1
Choose k = -1/2, then 1/k = -2.
Choose k = 1/2, then 1/k = 2.
Insufficient.
Answer is A.
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When you go from 1/(k-1) to (k-1), don't you change the inequality sign?GMATQuantCoach wrote:1. 1/(k-1) > 0
Then k - 1 > 0
k >1
Then 1/k > 0.
Sufficient.
When you go from 1/(k+1) to (k+1), don't you change the inequality sign?GMATQuantCoach wrote: 2. 1/(k+1)>0
k+1>0
k>-1
Choose k = -1/2, then 1/k = -2.
Choose k = 1/2, then 1/k = 2.
Insufficient.
GMATQuantCoach wrote: Answer is A.
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the fact that the question is 1/(k-1) is only there to throw you off.....
What is 1/(k-1) > 0 saying?
It is saying that k - 1 > 0
The 1 on the top is insignificant because is has no bearing on whether it is negative or positive.
So A) can be rephrased to k - 1 > 0
B) rephrased to k + 1 > 0
So in A) k HAS to be greater than 1 (making 1/k positive)
B) k<-1, meaning that k can be negative or positive so insufficient.
What is 1/(k-1) > 0 saying?
It is saying that k - 1 > 0
The 1 on the top is insignificant because is has no bearing on whether it is negative or positive.
So A) can be rephrased to k - 1 > 0
B) rephrased to k + 1 > 0
So in A) k HAS to be greater than 1 (making 1/k positive)
B) k<-1, meaning that k can be negative or positive so insufficient.
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Ahh... Thanks Mike22629.mike22629 wrote:the fact that the question is 1/(k-1) is only there to throw you off.....
What is 1/(k-1) > 0 saying?
It is saying that k - 1 > 0
The 1 on the top is insignificant because is has no bearing on whether it is negative or positive.
So A) can be rephrased to k - 1 > 0
B) rephrased to k + 1 > 0
So in A) k HAS to be greater than 1 (making 1/k positive)
B) k<-1, meaning that k can be negative or positive so insufficient.
Want to Beat GMAT.
Always do what you're afraid to do. Whoooop GMAT
Always do what you're afraid to do. Whoooop GMAT