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Data sufficiency (2)

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Data sufficiency (2)

by Lookingfor700GMAT » Thu Mar 11, 2010 6:24 am
Is 1/p > r/r^2 + 2?

p=r
r>0

I chose A by itself but the answer is C. Is this because the inequality would not hold if both p and r =0?
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by kstv » Thu Mar 11, 2010 10:24 am
the eq is 1/p> r/(r²+2)
if p=r then 1/r > r/(r²+2) if r = 2
1/2>2/6 1/2>1/3 0.5> .333
but if r = -2
-1/2 < - 1/3
- 0.5 < - .3 on the number line
we need the info that r > 0
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by DanaJ » Thu Mar 11, 2010 10:58 am
Moved to the appropriate forum. The GMAT Math is strictly for general questions. Use the PS and DS forums for questions!
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by diebeatsthegmat » Wed May 12, 2010 11:56 am
Lookingfor700GMAT wrote:Is 1/p > r/r^2 + 2?

p=r
r>0

I chose A by itself but the answer is C. Is this because the inequality would not hold if both p and r =0?
hi,
i will solve this problem by different way... i choose C for the answer and here is my solution.
1/p>r/(r^2+2)?
1. p=r
>>>> 1/r>r/(r^2+2) <=> 1/r-1/r^2+2 >0 <=> 2/r^3+2r>0
if r>0 ok, yes, 2/r^3+2r >0
if r<0 so no, >>>>> 1 is insuff
1. R>0 but what abot p? (N) 2 is insuff
1+2 is the answer
C
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