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Quadratic Equations

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by Brent@GMATPrepNow » Sun Sep 01, 2013 8:58 am
If x cannot equal 2, the [3x^2(x-2) - x + 2] / (x-2) =

A. 3x^2 - x + 2
B. 3x^2 + 1
C. 3x^2
D. 3x^2 - 1
E 3x^2 - 2
We have: [3x^2(x-2) - x + 2] / (x-2)
Notice that we can rewrite - x + 2 as - 1(x+2)

So, [3x^2(x-2) - x + 2] / (x-2) = [3x^2(x-2) - 1(x+2)] / (x-2)
= [(3x^2 - 1)(x+2)] / (x+2)
= 3x^2 - 1
= D

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by [email protected] » Sun Sep 01, 2013 12:42 pm
Hi vinay1983,

This type of question is perfect for TESTING values.

As a "nudge", try TESTING a value for X that is NOT equal to 2. You could use 3, for example.

Now, plug in X = 3 and calculate what the fraction equals. Then plug 3 into the answers and find the match.

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by sanjoy18 » Sun Sep 01, 2013 12:51 pm
the given equation is valid for any values of x except x=2

lets put x=0 in given equation.then it becomes 2/-2 = -1
now put x=0 in given option..only option D gives value -1 at x=0
hence the right answer

D
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