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In Episode 3 of our GMAT Ninja Critical Reasoning series, we tackle Discrepancy, Paradox, and Explain an Oddity questions. You know the feeling: the passage gives you two facts that seem completely contradictory....- May 05
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GMAT Inequalities is a high-frequency topic in GMAT Quant, but many students struggle because the concepts behave differently from standard algebra. Understanding the right rules, patterns, and edge cases can significantly improve both speed and accuracy. - May 08
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29 Sep 2006, 00:59
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Bookmarks
ok, did a little more thinking and i am changing my answer to E
i totally forgot about a, which could be negative.
so to continue my previous thread, i found a yes scenario when combining both statements, now i need to find a no scenario to spoil answer C--
to do this, let's look at
(x+1)(-x+2)
we have -x^2+x+2, where b+c is positive and bc is also positive but this time we have one negative root and one positive root
x=-1 or x=2
therefore INSUFF together
so answer is E
Cicerone, is this right??
i totally forgot about a, which could be negative.
so to continue my previous thread, i found a yes scenario when combining both statements, now i need to find a no scenario to spoil answer C--
to do this, let's look at
(x+1)(-x+2)
we have -x^2+x+2, where b+c is positive and bc is also positive but this time we have one negative root and one positive root
x=-1 or x=2
therefore INSUFF together
so answer is E
Cicerone, is this right??
29 Sep 2006, 02:32
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Bookmarks
Viperace
Woots, just found the mistake I made. However my answer doesnt changes
Question ask if both roots are positive
Only one condition for that is
b < -sqrt(b^2 - 4ac )
.
.
.
=> ac < 0
=> c <0 since given a>0
I) Sum of two root>0
This implies -b/a > 0
=> b <0
This is not sufficient to tell if c<0
II) Product of two root > 0
which means c/a>0 if u work it out
[-b + sqrt(b^2 - 4ac ) ]*[-b - sqrt(b^2 - 4ac ) ]/4a^2 >0
[b^2 - (b^2 - 4ac )]/4a^2>0
=> c/a >0
=> c > 0
Which is sufficient to answer the question. "both roots are positive?"NO
Condition from I) is not needed.
) 
