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Re: DS_ M03, question 19 [#permalink]
10 Jan 2008, 09:59
a , b , and c are integers. Is abc = 0?
1) a^2 = 2a 2) (b/c) = [[(a+b)^2] / [a^2 + 2ab + b^2]] - 1; where a does not equal -b and c does not equal 0;
Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient EACH statement ALONE is sufficient Statements (1) and (2) TOGETHER are NOT sufficient
Answer is B Statement 1: does not give any information about a.b.c---> Insufficient Statement 2: Can be rewrite as b/c = [(a+b)^2/(a+b)^2]-1 b/c = 1-1 = 0 which gives product of a,b and c is zero. Hence Sufficient
Re: a , b , and c are integers. Is abc = 0? 1) a^2 = 2a 2) (b/c) [#permalink]
05 Jul 2013, 11:16
This post was BOOKMARKED
I saw this question in a gmat club test, and I still have some doubts about the answer.
How can i reduce the expresion [(a+b)^2/(a+b)^2], if we don't know whether (a+b)^2 is 0 or not. ¿??
Thanks in advance for your help!
BELOW IS REVISED VERSION OF THIS QUESTION:
Is \(abc = 0\) ?
In order \(abc = 0\) to be true at least one of the unknowns must be zero.
(1) \(a^2 = 2a\) --> \(a^2-2a=0\) --> \(a(a-2)=0\) --> \(a=0\) or \(a=2\). If \(a=0\) then the answer is YES but if \(a=2\) then \(abc\) may not be equal to zero (for example consider: \(a=2\), \(b=3\) and \(c=4\)). Not sufficient.