If you're experiencing a roadblock with one of the Manhattan Prep GMAT math strategy guides, help is here!
sharifa
Forum Guests
 
Posts: 1
Joined: Wed Sep 07, 2011 9:16 am
 

Algebra Question Bank, #9

by sharifa Fri Aug 24, 2012 5:05 am

Hi, I have a question regarding Question 9 from the Algebra Question Bank:

It asks:

If r is not equal to 0, is

r2/|r| < 1?

(1) r > -1

(2) r < 1


I got this question wrong because I simplified the question stem to "r(r)/r <1" and then "r<1" which led me to pick B on this DS question. I am guessing I wasn't allowed to simplify the question stem in this way but I cannot figure out why.
yinliqiu
Forum Guests
 
Posts: 8
Joined: Thu Aug 16, 2012 8:59 pm
 

Re: Algebra Question Bank, #9

by yinliqiu Fri Aug 24, 2012 8:48 pm

sharifa.monawer Wrote:Hi, I have a question regarding Question 9 from the Algebra Question Bank:

It asks:

If r is not equal to 0, is

r2/|r| < 1?

(1) r > -1

(2) r < 1


I got this question wrong because I simplified the question stem to "r(r)/r <1" and then "r<1" which led me to pick B on this DS question. I am guessing I wasn't allowed to simplify the question stem in this way but I cannot figure out why.


Hi, I think you ignore that both squares and absolute value can make negative become positive. For instance, if r = -2, which satisfy r<1, the result is (-2)^2/|-2|=2. it will be greater than 1.
So I think the answer should be C. Only if -1<r <1, r^2/|r| < 1

I don't know if my explantion is clear enough for you.
jnelson0612
ManhattanGMAT Staff
 
Posts: 2664
Joined: Fri Feb 05, 2010 10:57 am
 

Re: Algebra Question Bank, #9

by jnelson0612 Sun Aug 26, 2012 2:17 pm

yinliqiu Wrote:
sharifa.monawer Wrote:Hi, I have a question regarding Question 9 from the Algebra Question Bank:

It asks:

If r is not equal to 0, is

r2/|r| < 1?

(1) r > -1

(2) r < 1


I got this question wrong because I simplified the question stem to "r(r)/r <1" and then "r<1" which led me to pick B on this DS question. I am guessing I wasn't allowed to simplify the question stem in this way but I cannot figure out why.


Hi, I think you ignore that both squares and absolute value can make negative become positive. For instance, if r = -2, which satisfy r<1, the result is (-2)^2/|-2|=2. it will be greater than 1.
So I think the answer should be C. Only if -1<r <1, r^2/|r| < 1

I don't know if my explantion is clear enough for you.


Thank you! Yes, your explanation makes sense to me; Sharifa, let us know if we can help you further.
Jamie Nelson
ManhattanGMAT Instructor