OG #133

[JGaynor]

I can solve algebra, but I'm not understanding this one...not even when looking at the solution...

If x ≠2, then 3x²(x-2)-x+2/x-2 = ?

A) 3x²-x+2
B) 3x+1
C) 3x²
D) 3x²-1
E) 3x²-2

Thank you!

[neoreaves]

Is there a typo in this ?

Lets take x = 1

then 3x²(x-2)-x+2/x-2 = 3(1)(-1) - (3)/(-1) = -3 + 3 = 0

A) 3x²-x+2 = 4
B) 3x+1 = 4
C) 3x² = 3
D) 3x²-1 =2
E) 3x²-2 = 1

NONE of the choices gives us a 0. So please check and post the correct question.

[this_time_i_will]

Take x-2 common. So the given equation may be re-written as:
(x-2)(3x^2-1)/(x-2)
=3x^2-1.
So D

[JGaynor]

Take x-2 common. So the given equation may be re-written as:
(x-2)(3x^2-1)/(x-2)
=3x^2-1.
So D

Thank you for the quick reply...can you be more specific on how you obtained (3x²-1) part though?

[neoreaves]

ok first of ....this question is not OG #133 ... I have checked OG 10,11,12 editions ...this question is not there ...atleast at #133 ...


secondly, if "this_time" solved it right ...then JGaynor has posted the question wrong because it should be :

(3x²(x-2)-x+2 )/ (x-2)


So please read Sudhir's post about re-checking before posting ...

and please go over the high school algebra book that talks about the use of paranthesis !!!

[suryapal]

3x^2(x-2)-1(x-2)/(x-2) = (x-2)(3x^2-1)/(x-2) = (3x^2-1) so D is the answer

[JGaynor]

ok first of ....this question is not OG #133 ... I have checked OG 10,11,12 editions ...this question is not there ...atleast at #133 ...


secondly, if "this_time" solved it right ...then JGaynor has posted the question wrong because it should be :

(3x²(x-2)-x+2 )/ (x-2)


So please read Sudhir's post about re-checking before posting ...

and please go over the high school algebra book that talks about the use of paranthesis !!!

I made a mistake its #133 out of another guide, I didn't realize it. But regardless, the question is posted correctly and you aren't able to figure it out, so you should review your high school math too!

Thank you to the others who helped!

[JGaynor]

ok first of ....this question is not OG #133 ... I have checked OG 10,11,12 editions ...this question is not there ...atleast at #133 ...


secondly, if "this_time" solved it right ...then JGaynor has posted the question wrong because it should be :

(3x²(x-2)-x+2 )/ (x-2)


So please read Sudhir's post about re-checking before posting ...

and please go over the high school algebra book that talks about the use of paranthesis !!!

I made a mistake its #133 out of another guide, I didn't realize it. But regardless, the question is posted correctly and you aren't able to figure it out, so you should review your high school math too!

Thank you to the others who helped!

[neoreaves]

ok first of ....this question is not OG #133 ... I have checked OG 10,11,12 editions ...this question is not there ...atleast at #133 ...


secondly, if "this_time" solved it right ...then JGaynor has posted the question wrong because it should be :

(3x²(x-2)-x+2 )/ (x-2)


So please read Sudhir's post about re-checking before posting ...

and please go over the high school algebra book that talks about the use of paranthesis !!!

I made a mistake its #133 out of another guide, I didn't realize it. But regardless, the question is posted correctly and you aren't able to figure it out, so you should review your high school math too!

Thank you to the others who helped!

I am glad you realized your one mistake out of the 2 .....just plug in value of 1 ...none of the choices you have given, gives us the answer ....how is that possible ?? ....I have seen the posts of the guys who have put down their answers ...but to be honest none of them have yet justified how they have opened the parenthesis correctly ... just to clarify

(3x²(x-2)-x+2 )/ (x-2) is not equal to 3x²(x-2)-x+2/x-2 ---- No matter how many times you look at this ...they don't magically become equal .....

[JGaynor]

The question is out of the the thin green quantitative review book- its a supplement with the official guide

It is written exactly: 3x²(x-2)-x+2/x-2 =

The solution states: As a first step, the numerator must be factored so that the numerator is the product of two or more expressions, one of which is (x-2). This can be accomplished by rewriting the last two terms of the numerator as (-1)(x-2). Then 3x²(x-2)-x+2/x-2 = 3x²(x-2)+(-1)(x-2)/x-2 = (x-2)(3x²-1)/x-2 = 3x²-1

Apparently I don't recall going over problems to make the numerator of 2 or more expressions so this problem is tricking me a bit.

[neoreaves]

The question is out of the the thin green quantitative review book- its a supplement with the official guide

It is written exactly: 3x²(x-2)-x+2/x-2 =

The solution states: As a first step, the numerator must be factored so that the numerator is the product of two or more expressions, one of which is (x-2). This can be accomplished by rewriting the last two terms of the numerator as (-1)(x-2). Then 3x²(x-2)-x+2/x-2 = 3x²(x-2)+(-1)(x-2)/x-2 = (x-2)(3x²-1)/x-2 = 3x²-1

Apparently I don't recall going over problems to make the numerator of 2 or more expressions so this problem is tricking me a bit.

Ok then my apologies ....if this is how GMAT writes questions then im toast ....i mean i look at this -x + 2 /x - 2 .....if we go by the rules of BODMAS ....division first ....so we should divide 2/x before we subtract .....GMAC should do a better job of keeping the paranthesis and everything clear ....

[harshavardhanc]

The question is out of the the thin green quantitative review book- its a supplement with the official guide

It is written exactly: 3x²(x-2)-x+2/x-2 =

The solution states: As a first step, the numerator must be factored so that the numerator is the product of two or more expressions, one of which is (x-2). This can be accomplished by rewriting the last two terms of the numerator as (-1)(x-2). Then 3x²(x-2)-x+2/x-2 = 3x²(x-2)+(-1)(x-2)/x-2 = (x-2)(3x²-1)/x-2 = 3x²-1

Apparently I don't recall going over problems to make the numerator of 2 or more expressions so this problem is tricking me a bit.

Ok then my apologies ....if this is how GMAT writes questions then im toast ....i mean i look at this -x + 2 /x - 2 .....if we go by the rules of BODMAS ....division first ....so we should divide 2/x before we subtract .....GMAC should do a better job of keeping the paranthesis and everything clear ....

neoreaves,

apparently, everyone involved in this discussion is correct in his own way. There is nothing wrong anywhere.

The problem lies our inability to draw the division sign correctly in these posts. Think, in the book/text the division would be shown as a long line "__________" , which will cover the complete denominator (in our case x-2). There is no need to have parentheses for x-2. So, GMAC or the questions in GMAT will be unambiguous.

The problem comes when you are reproducing the same question here. You just have a slash to signify division, and which will cover only a single character beside it. In order to show division by x-2., you will have to use parentheses in your version.

So, peace it is and everyone is right! I see smiling faces!

[neoreaves]

yes indeed !