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# M03 #19

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Joined: 01 Mar 2013
Posts: 20
Schools: HBS '16
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Re: M03 #19 [#permalink]  25 May 2013, 10:39
Thank you Bunuel for clarifying d doubt

Bunuel wrote:
crackgmat2013 wrote:
guptasulabh7 wrote:
(A)a(a-2) = 0

a = 0 or a =2

In sufficient
b/c = ((a+b)^2 - (a+b)^2)/(a+b)^2

b/c=0

b=0

Sufficient

Ans:B

Is this the right simplification for statement 1:-

I got only 1 value for a i.e. a=2

a square = 2a
a * a = 2a
a = 2

if its not correct simplification please explain, why?

Yes, that's not correct.

Never reduce an equation by a variable (or expression with a variable), if you are not certain that the variable (or the expression with a variable) doesn't equal to zero. We can not divide by zero.

So, if you divide (reduce) a^2=a by a you assume, with no ground for it, that a does not equal to zero thus exclude a possible solution (notice that both a=2 AND a=0 satisfy the equation).

Hope it's clear.
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Re: M03 #19   [#permalink] 25 May 2013, 10:39
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# M03 #19

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