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which is the smallest value of x for which (12/x +36)((4-x^2

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by mitzwillrockgmat » Sun May 23, 2010 5:52 am
which is the smallest value of x for which (12/x +36)((4-x^2)=0

a. -3
b. -2
c. -1/2
d. -1/4
e. 2

to approach this, i saw that the product of the two numbers had to equal to 0. hence, one of the numbers is 0. i considered the 2nd number, 4-x^2 first as its simpler. to make this zero, x can be + or - 2. hence, b or e is the answer.

now how do i decide between these two??

12/x = -36 & substituting both 2 and -2 doesn't help!

12/2 => 6 = -36 while 12/-2 => -6 =-36

WHAT AM I MISSING HERE?????
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Source: — Problem Solving |

by thephoenix » Sun May 23, 2010 6:09 am
since the q is asking for smallest value of x ans will be -2
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by mitzwillrockgmat » Sun May 23, 2010 6:11 am
thephoenix wrote:since the q is asking for smallest value of x ans will be -2
lol opps! thanks!
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by gmatjedi » Sun May 23, 2010 6:26 am
12/x+36=0
so x=-1/3

or

4-x^2=0
so (2-x)(2+x)=0
so x=2, -2

smallest number among -2, -1/3, and 2= -2
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by neha.patni » Sun May 23, 2010 9:46 pm
mitzwillrockgmat wrote:which is the smallest value of x for which (12/x +36)((4-x^2)=0

a. -3
b. -2
c. -1/2
d. -1/4
e. 2

to approach this, i saw that the product of the two numbers had to equal to 0. hence, one of the numbers is 0. i considered the 2nd number, 4-x^2 first as its simpler. to make this zero, x can be + or - 2. hence, b or e is the answer.

now how do i decide between these two??

12/x = -36 & substituting both 2 and -2 doesn't help!

12/2 => 6 = -36 while 12/-2 => -6 =-36

WHAT AM I MISSING HERE?????
IMO B

Because the question has asked for the smallest value of X which is -2 not 2
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