Is x 6? (1) x^2 = 49 (2) 7x = x^2

Question

Is x > 6?

(1) x^2 = 49
(2) 7x = x^2

gmatexam439 · Answer

Statement 1:  
x=7 / -7 -- Insufficient

Statement 2:  
 x^2  - 7x = 0
x(x-7) = 0
x=0 / 7 -- Insufficient

Statement 1 & 2: 
x=7 -- Sufficient

IMO "C" is correct

chandan1988 · Answer

Statement 1:

X^2= 49
X= +7/-7
Insufficient

7X=X^2
X(X-7)=0
X= 0,7
Insufficient

Taking both the statement
X=7 sufficient
Ans: C

Correct me if I am wrong .

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francod9 · Answer

Hello,

Could we solve Statement #2 this way?
(2) 7x = x^2
 7x = x*x
divide both sides by x to get
 7=x
Is this correct? and if so, sufficient?

chetan2u · Answer

No you cannot..
You do not whether the variable 'x' is Positive or NEGATIVE..
If NEGATIVE, you can't divide by that variable..

Take it to one side  7x=x^2…....x^2-7x=0......x(x-7)=0 
So x can be 0 or 7

francod9 · Answer

Thank you! <img src="{SMILIES_PATH}/1f44d-1f3fb.png" class="forumSmileyItem" width="20" height="20" alt=":thumbup:" title="Thumbup" />

GMATBusters · Answer

I don't agree with the below statement.
Since  (2) 7x = x^2  is an equation, it doesn't matter whether x is negative or positive, we can divide by x on both sides of the equation
But yes we don't know that whether x is zero or non nero number, so we cannot divide by x.

please confirm my understanding.

,

bumpbot · Answer

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Is x > 6? (1) x^2 = 49 (2) 7x = x^2

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