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Mclaughlin: Master | Next Rank: 500 Posts; Posts: 131; Joined: Mon May 05, 2008 10:46 am; Thanked: 1 times

by Mclaughlin » Sat Aug 09, 2008 5:12 pm

what is the value of X

1. x^2 - 9 = 16
2. 3x(x-5) = 0

OA is C but I got B because I solved B and got a value for X.

Source: Beat The GMAT — Data Sufficiency | Sat Aug 09, 2008 5:12 pm

sibbineni: Master | Next Rank: 500 Posts; Posts: 222; Joined: Fri Jan 04, 2008 8:10 pm; Thanked: 15 times

by sibbineni » Sun Aug 10, 2008 8:09 pm

st1. x^2 - 9 = 16

x^2=25

x=+/-5 insuff
st2. 3x(x-5) = 0

3x=0 or (x-5)=0

x=0 or x=5

insuff

together(1) and (2)

x=5

sufficient
IMOC

pepeprepa: Legendary Member; Posts: 661; Joined: Tue Jul 08, 2008 12:58 pm; Location: France; Thanked: 48 times

by pepeprepa » Mon Aug 11, 2008 3:06 am

You cannot find an unique value of X with 2) only. Check your error.

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