gmatprep k does not = 1,0,1, is (1/k) > 0?
1. 1/(k1)>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?
This topic has expert replies

 Senior  Next Rank: 100 Posts
 Posts: 44
 Joined: 28 Jun 2009
 Location: Online
 Thanked: 13 times
 GMAT Score:51
1. 1/(k1) > 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.
FREE Weekly Online Office Hours
Upcoming FREE Online Class: Effective Calculations  11/15/09 Sunday
Instructor  GMATPrepMath.com  GMAT Prep Courses Starting at $60 with FREE GMAT Math Formula Sheet
Choose from Topics:
Number Properties  Advanced Counting (Combinatorics)  Probability  Advanced Algebra in DS  Geometry  Word Problems  Fundamental Algebra in PS  Effective Calculations
Upcoming FREE Online Class: Effective Calculations  11/15/09 Sunday
Instructor  GMATPrepMath.com  GMAT Prep Courses Starting at $60 with FREE GMAT Math Formula Sheet
Choose from Topics:
Number Properties  Advanced Counting (Combinatorics)  Probability  Advanced Algebra in DS  Geometry  Word Problems  Fundamental Algebra in PS  Effective Calculations

 Master  Next Rank: 500 Posts
 Posts: 431
 Joined: 10 Jan 2009
 Thanked: 16 times
 Followed by:1 members
When you go from 1/(k1) to (k1), don't you change the inequality sign?GMATQuantCoach wrote:1. 1/(k1) > 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.
Want to Beat GMAT.
Always do what you're afraid to do. Whoooop GMAT
Always do what you're afraid to do. Whoooop GMAT

 Master  Next Rank: 500 Posts
 Posts: 322
 Joined: 27 Mar 2009
 Thanked: 24 times
 GMAT Score:710
the fact that the question is 1/(k1) is only there to throw you off.....
What is 1/(k1) > 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/(k1) > 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.

 Master  Next Rank: 500 Posts
 Posts: 431
 Joined: 10 Jan 2009
 Thanked: 16 times
 Followed by:1 members
Ahh... Thanks Mike22629.mike22629 wrote:the fact that the question is 1/(k1) is only there to throw you off.....
What is 1/(k1) > 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