Q from MGMAT Challenge Problem 25 Mar 10

[aimhier]

Hi experts，

X is replaced by 1-X everywhere in the expression 1/x-{1/(1-x)}, with x not equal 0 , the outcome equals

(A) x+1
(B) x-1
(C) 1-{x^2}
(D) 2x-1
(E) 1-2x

in the final step of solution, why we have to multiply Xsquare-x ?

thanks

[RonPurewal]

Hi experts，

X is replaced by 1-X everywhere in the expression 1/x-{1/(1-x)}, with x not equal 0 , the outcome equals

(A) x+1
(B) x-1
(C) 1-{x^2}
(D) 2x-1
(E) 1-2x

in the final step of solution, why we have to multiply Xsquare-x ?

thanks

hi,
please quote the solution that you're citing here; otherwise, it's impossible to tell what you are talking about (and this thread will be useless to readers who happen to come across it).

thanks.

[aimhier]

Hi Ron，
the Q is from Manhattan GMAT Challenge Problem of the Week - 25 Mar 10

http://www.beatthegmat.com/mba/2010/03/ ... -25-mar-10

Thank you

[RonPurewal]

Hi experts，

X is replaced by 1-X everywhere in the expression 1/x-{1/(1-x)}, with x not equal 0 , the outcome equals

(A) x+1
(B) x-1
(C) 1-{x^2}
(D) 2x-1
(E) 1-2x

in the final step of solution, why we have to multiply Xsquare-x ?

whoa yeah, i don't really see what's up with that step, either. i will get in touch with the people who maintain the challenge problem bank and ask them what the deal is.
stay tuned

[StaceyKoprince]

Hi, guys

The problem as published on BTG is wrong. Every now and then, they have issues with their publishing software and some text of an already-published article gets chopped out (without anyone knowing about it until a student says "Hey, what's up with this?"). I've had this happen on several of my articles in the past.

The real problem also includes this information:
x does not equal 1

And this is the full question: If the result is then multiplied by x^2 - x, then the outcome equals

As you can see, that changes the entire problem. Wanna try it again? :)