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PS - OG 122

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PS - OG 122

by vinviper1 » Wed Mar 26, 2008 10:35 am
An operation * is defined by the equation a*b = a-b/a+b, for all numbers a and b such tht
a doesnt equal -b
a doesnt eual -c

a*c = 0

then c =
-a
-1/a
0
1/a
a

E
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by xilef » Wed Mar 26, 2008 10:43 am
a*c = 0 or
a-c/a+c=0

we know that a+c cannot be equal to 0 so for the equation to hold true, a-c must be equal to 0.

a-c=0
c=a

Answer E.
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by Fiji_surf » Fri Jul 04, 2008 10:40 am
Can someone please explain this.

Why
a*c = 0 or
a-c/a+c=0

Thanks.
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by Poornima » Fri Jul 04, 2008 10:44 am
Fiji,

a*c=0 is a part of the question stem :)
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by Poornima » Fri Jul 04, 2008 10:45 am
Fiji,

a*c=0 is a part of the question stem :)
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by Fiji_surf » Fri Jul 04, 2008 10:53 am
Poornima,

The operation * is not a multiplication. It is some unknown operation as defined in the first sentence of the question.

(It is from GMAT review 11 th edition. Question 122. And I just do not undersstand the explanation in the answer section.).
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by Fiji_surf » Fri Jul 04, 2008 11:00 am
Suddenly everything became clear!
I am an idiot: it took me so long - probably I need a break.
thanks for help.
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