Register    Login    Search    Rss Feeds

Forums Home » Ask An Instructor » GMAT Math » GMAT Prep Math


 Page 1 of 1 [ 3 posts ] 



  Print view Print view Previous topic Previous topic | Next topic Next topic
 

DS with absolute value

Author Message
susan.meng
 Post subject: DS with absolute value
 Post Posted: Mon Jul 20, 2009 9:38 pm 
Offline
Course Students


Posts: 10
Is sqrt ((x-5)^2) = 5 - x?
1. -x*abs(x) > 0
2. 5-x>0
Top 
mxs2009
 Post subject: Re: DS with absolute value
 Post Posted: Tue Jul 21, 2009 1:44 am 
Offline
Students


Posts: 16
This question can be rephrased as: is 5-x > 0? Or, more specifically, is x<5 because the left side of the equation can never be negative (the square root of a number cannot be negative in GMAT math)

(1) -x*|x|>0
The absolute value must be positive so we have -x*(a positive number)>0
Thus, x must be negative. x<0. SUFFICIENT

(2) 5-x>0 (subtract each side by 5)
-x>-5 (divide by negative 1)
x<5 (don't forget to switch the signs)
SUFFICIENT

Answer is D
Top 
RonPurewal
 Post subject: Re: DS with absolute value
 Post Posted: Tue Jul 21, 2009 7:46 pm 
Offline
ManhattanGMAT Staff


Posts: 7146
this question is very similar to the following one, so take a look at it.

(in fact, the problem statement is EXACTLY the same; the only difference is that a "5" has been substituted for the "3")

is-sqrt-x-3-2-3-x-t7258.html
Top 
Display posts from previous:  Sort by  
 
 Page 1 of 1 [ 3 posts ] 





Who is online

Users browsing this forum: No registered users and 0 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: