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A challenging inequality question...

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A challenging inequality question...

by woo » Sun Aug 02, 2009 6:33 am
If x, y, and z are integers, is x+y^2+3z>=0 ?

(1) y>= zero
(2) x<=0 and z<=0

It is from one of posts in this forum.

The poster said OA is B but I cannot see why..

I think it is E.

Please, share your thoughts.
Last edited by woo on Wed Aug 05, 2009 4:38 am, edited 3 times in total.
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Source: — Data Sufficiency |
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by shahdevine » Sun Aug 02, 2009 7:28 am
could you clarify what the questions is?

is it asking is x+y^2+3z=>0?

you have a typo.
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by woo » Mon Aug 03, 2009 5:08 am
sorry..

No wonder why I got only one reply even after a day..

Thanks!
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by woo » Wed Aug 05, 2009 4:40 am
Anyone interested in this question?
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by pradeepsarathy » Thu Aug 06, 2009 11:46 am
IMO E as well.

Explanation -

Stmt 1 -
Does not talk about x and z.
Hence Insufficient

Stmt 2 -
Plug in values

Let x = -1 and z = -4 then x+3z = -13. Although 'Y^2' evaluates to a positive value, we don't know its exact value.
Hence Insufficient

Combining Stmt 1 and Stmt 2 -

Let's plug some values -

Case 1: x = -1, y = 2, z = -4 => evaluates to -9 <0
Case 2: x = -1, y = 6, z = -4 => evaluates to 23 >0
Case 3: x = 0, y = 0, z = 0 => evaluates to 0 = 0

Hence Insufficient

Any idea, how the other poster got the OA as 'B'
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