tough n confusing

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Source: — Data Sufficiency |

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by arora007 » Sat Jan 15, 2011 11:11 am
according to 1)
x* =x
x(x-1) = x

thus x^2 -x =x
=> x^2 -2x = 0
=> x(x-2)=0
INSUFFICIENT

(X - 1 ) * = (X - 2)

(X-1)(X-2) =(X-2)
X^2 -3X +2 =X-2
X^2 -4X +4 =0
(X-2)^2=0

SUFFICIENT

answer is B
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by nehatandon » Sat Jan 15, 2011 7:01 pm
arora007 wrote:according to 1)
x* =x
x(x-1) = x

thus x^2 -x =x
=> x^2 -2x = 0
=> x(x-2)=0
INSUFFICIENT

(X - 1 ) * = (X - 2)

(X-1)(X-2) =(X-2)
X^2 -3X +2 =X-2
X^2 -4X +4 =0
(X-2)^2=0

SUFFICIENT

answer is B
perfect solution, arora007!