Inequality Trouble

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anantbhatia: Senior | Next Rank: 100 Posts; Posts: 98; Joined: Sat Feb 06, 2010 11:56 pm; Thanked: 5 times

Inequality Trouble

by anantbhatia » Fri Sep 10, 2010 10:34 pm

Hi all,

Inequalities are still troubling me. The following qn is from a set, most probably previous GMAT qns:-

If x(x - 5)(x + 2) = 0, is x negative?
(1) x^2 - 7x â‰ 0
(2) x^2 -2x -15 â‰ 0

OA C
I am not able to get a hold on such DS. Any guidance will be highly appreciated.

Quote

Source: Beat The GMAT — Data Sufficiency | Fri Sep 10, 2010 10:34 pm

pradeepkaushal9518: Legendary Member; Posts: 1309; Joined: Wed Mar 17, 2010 11:41 pm; Thanked: 33 times; Followed by:5 members

by pradeepkaushal9518 » Fri Sep 10, 2010 11:20 pm

x(x-5)(x+2)=0 is x positive?

1.x^2-7x is not=0

x=0 , 5 and -2

x^2-7x

for x=0 the above is true
x=5 the above is true
x=-2 the above is true so 1 is true only when x is both positive and negative so insuff A and D out

2.x^2-2x-15 is not equal to 0

for x=0 2 is true
x=5 2 is not true
x= -2 is true again x may be positive or negative so insuff B is out left with c and E

combine 1 and 2 for x= -2 both are satisfied hence it is negative 0 also satisfy this so x is either 0 or negative but not positive

so C

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