|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Updated on: 20 Oct 2013, 04:43
Originally posted by jellybean23 on 19 Oct 2013, 12:14.
Last edited by Bunuel on 20 Oct 2013, 04:43, edited 1 time in total.
Last edited by Bunuel on 20 Oct 2013, 04:43, edited 1 time in total.
Edited the question and added the OA.
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
75%
(hard)
Question Stats:
57% (02:27) correct
43%
(02:00)
wrong
based on 270
sessions
History
Date
Time
Result
Not Attempted Yet
If a^n ≠ 0 and n is a positive integer, is n odd?
(1) a^n + a^(n+1) < 0
(2) a is an integer.
(1) a^n + a^(n+1) < 0
(2) a is an integer.
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
19 Oct 2013, 13:42
Kudos
Bookmarks
Statement 1:
This essentially says \(a\) is negative and thereby one of the terms \(a^n\) or \(a^n^+^1\) is negative (both can't be negative as either \(n\) is even or \(n+1\) is even)
Let's assign \(a=-2\). So \(a^n + a^n^+^1 < 0\) only when \(n\) is even. But what happens if \(a\) is not an integer? Assign \(a=-0.1\), then for the equation to be less than zero, \(n\) has to be odd. INSUFFICIENT
Statement 2:
This tells us that \(a\) is an integer, but does not say anything about \(n\). INSUFFICIENT
Statement 1 & 2: as discussed under Statement 1, when \(a\) is a negative integer, \(n\) has to be even for the equation to be less than zero. So we know \(n\) is not odd. SUFFICIENT
Answer is C.
This essentially says \(a\) is negative and thereby one of the terms \(a^n\) or \(a^n^+^1\) is negative (both can't be negative as either \(n\) is even or \(n+1\) is even)
Let's assign \(a=-2\). So \(a^n + a^n^+^1 < 0\) only when \(n\) is even. But what happens if \(a\) is not an integer? Assign \(a=-0.1\), then for the equation to be less than zero, \(n\) has to be odd. INSUFFICIENT
Statement 2:
This tells us that \(a\) is an integer, but does not say anything about \(n\). INSUFFICIENT
Statement 1 & 2: as discussed under Statement 1, when \(a\) is a negative integer, \(n\) has to be even for the equation to be less than zero. So we know \(n\) is not odd. SUFFICIENT
Answer is C.
fnumiamisburg
Joined: 10 Sep 2013
Last visit: 25 Jun 2019
Posts: 28
Given Kudos: 19
Location: United States
Concentration: Strategy, Operations
Schools: Fisher '16 Kelley '16 CUHK '16 Kellogg 1YR '15
GMAT Date: 12-10-2013
GPA: 3.5
WE:Operations (Manufacturing)
19 Oct 2013, 20:11
Kudos
Bookmarks
n >0
Statement 1 :
a^n + a^(n+1) < 0
lets put n =1 (odd) , a+a^2 <0 .................. , that means 0 > a > -1,
lets put n=2 (even) , a^2 + a^3 < 0 ........... , that means a < 0
but no info about a so no conclusion about n.. Insufficient..
Statement 2 :
a is an integer , but no conclusion about n... insufficient...
Taking both statements together....
only n=2 valid .... which gives n is not an odd no..
Answer C
Statement 1 :
a^n + a^(n+1) < 0
lets put n =1 (odd) , a+a^2 <0 .................. , that means 0 > a > -1,
lets put n=2 (even) , a^2 + a^3 < 0 ........... , that means a < 0
but no info about a so no conclusion about n.. Insufficient..
Statement 2 :
a is an integer , but no conclusion about n... insufficient...
Taking both statements together....
only n=2 valid .... which gives n is not an odd no..
Answer C
