Forum Home > GMAT > Quantitative > Problem Solving (PS)
Events & Promotions
|
|
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.
Dec 1511:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease.
Dec 1410:00 AM EST
-12:00 PM EST
Think a 100% GMAT Verbal score is out of your reach? Target Test Prep will make you think again! Our course uses techniques such as topical study and spaced repetition to maximize knowledge retention and make studying simple and fun.- Dec 14
11:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test. 
Dec 1608:00 AM PST
-11:59 PM PST
GMAT Club 12 Days of Christmas is a 4th Annual GMAT Club Winter Competition based on solving questions. This is the Winter GMAT competition on GMAT Club with an amazing opportunity to win over $40,000 worth of prizes!- Dec 17
09:00 AM PST
-10:00 AM PST
Join Manhattan Prep instructor Whitney Garner for a fun—and thorough—review of logic-based (non-math) problems, with a particular emphasis on Data Sufficiency and Two-Parts. - Dec 18
10:00 AM PST
-11:00 AM PST
Here is the essential guide to securing scholarships as an MBA student! In this video, we explore the various types of scholarships available, including need-based and merit-based options.
17 Sep 2010, 17:05
Kudos
Bookmarks
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
77% (01:14) correct
23%
(01:44)
wrong
based on 35
sessions
History
Date
Time
Result
Not Attempted Yet
If x is an integer, is \(9^x + 9^-^x = b\)?
(1) \(3^x + 3^-^x = \sqrt{b + 2}\)
(2) \(x > 0 = b\)
PROPER VERSION OF THIS QUESTION IS HERE: if-x-is-an-integer-is-9-x-9-x-b-139874.html
(1) \(3^x + 3^-^x = \sqrt{b + 2}\)
(2) \(x > 0 = b\)
The OA is A. I couldn't piece together (1) (I understand it now with the book's explanation), but I had answered B for this one. Why is the answer not D? (2) should be sufficient, because it gives you b = 0, and \(9^x + 9^-^x\) can't possibly be 0. So the answer would be NO and (2) should be sufficient.
PROPER VERSION OF THIS QUESTION IS HERE: if-x-is-an-integer-is-9-x-9-x-b-139874.html
This Question is Locked Due to Poor Quality
Hi there,
The question you've reached has been archived due to not meeting our community quality standards. No more replies are possible here.
Looking for better-quality questions? Check out the 'Similar Questions' block below
for a list of similar but high-quality questions.
Want to join other relevant Problem Solving discussions? Visit our Data Sufficiency (DS) Forum
for the most recent and top-quality discussions.
Thank you for understanding, and happy exploring!
17 Sep 2010, 17:25
Kudos
Bookmarks
TehJay
If x is an integer, is \(9^x + 9^-^x = b\)?
(1) \(3^x + 3^-^x = \sqrt{b + 2}\)
(2) \(x > 0 = b\)
(1) \(3^x + 3^-^x = \sqrt{b + 2}\)
(2) \(x > 0 = b\)
The OA is A. I couldn't piece together (1) (I understand it now with the book's explanation), but I had answered B for this one. Why is the answer not D? (2) should be sufficient, because it gives you b = 0, and \(9^x + 9^-^x\) can't possibly be 0. So the answer would be NO and (2) should be sufficient.
Is \(9^x + 9^{-x} = b\)?
(1) \(3^x + 3^-^x = \sqrt{b + 2}\) --> square both sides --> \(9^x+2*3^x*\frac{1}{3^x}+9^{-x}=b+2\) --> \(9^x + 9^{-x} = b\). So answer to the question is YES. Sufficient.
(2) \(x > 0 = b\) --> question becomes: is \(9^x+9^{-x}=0\)? Answer to this question would be NO, as LHS is the sum of two positive values and thus can not equal to zero. So, sufficient.
There must be something wrong with this question. Technically answer would be D, as EACH statement ALONE is sufficient to answer the question.
But even though formal answer to the question is D (EACH statement ALONE is sufficient), this is not a realistic GMAT question, as: on the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other.
So we can not have answer YES from statement (1) and answer NO from statement (2), as in this case statements would contradict each other.
I guess there is a typo in statement (2) and it should just state \(x>0\) instead of \(x>0=b\) (I've never seen such a notation in official sources).
Hope it helps
18 Sep 2010, 00:39
Kudos
Bookmarks
I have seen this question before. Though I don't remember the exact statement (2) but I am sure there was no ambiguity and that the two statements led to the same answer
As bunuel said it was most likely x>0
Posted from my mobile device
As bunuel said it was most likely x>0
Posted from my mobile device
