DS !!

[kishankolli]

Is x positive?

(1) (x - 3)2 > 0

(2) x3 - 1 > 0

Hello !! the first part is (x-3) whole square and the second part is x cube (x3). I would not like to reveal the solution. For some reason I do not agree with the solution given by MGAT in this question. I am checking to see if I have really missed something..Can you please help ??

[tgt.ivyleague]

Hi there .....

I feel that the answer should be B alone.

Do let me know whether this is right ? If it is, then i shall explain .... else, i shall join you in your wait for the right explanation !!!

Regards ...... Sam

[adiagr]

Is x positive?

(1) (x - 3)2 > 0

(2) x3 - 1 > 0

Hello !! the first part is (x-3) whole square and the second part is x cube (x3). I would not like to reveal the solution. For some reason I do not agree with the solution given by MGAT in this question. I am checking to see if I have really missed something..Can you please help ??

Hi,

From (1)

(x-3)^2 will always be positive and so we cannot get anything out of here. Insufficient.

From (2)
Given x^3 - 1 > 0

which means x^3>1

This is only possible when x>1.

Hence x is positive. Thus B is sufficient.

Alternatively
We can see that x^3 is positive from (2)

Now x^3 can be written as x^2.(x)

Now x^2 is always positive. This means that x is positive.

Sufficient.

Aditya

[kishankolli]

At the first instance I got "B". But when I looked at the answer, it was D.

1>(x-3)^2>0

=x^2-6x+9
=x^2 - 3x -3x +9
=x(x-3)-3(x-3)
=(x-3)(x-3)
i.e x = +3

I am not able to find the exact explanation in MGMAT, but I made a note of the solution..

[mschwrtz]

kishankolli, if I understand your posts, you give two different versions of S1: first (x-3)^2>0, and later 1>(x-3)^2>0.

The first version is equivalent to "x does not equal 3," which is not sufficient.

For the second version, focus just on the 1>(x-3)^2. This means that sqrt1>|x-3|, or -1<x-3<1, or 2<x<4. This implies that x>0. This is sufficient.

[yousuf_azim]

Hey guys,

Why u not give the ans straight forward?

BR

[jnelson0612]

The answer is B.