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cardoc: Junior | Next Rank: 30 Posts; Posts: 11; Joined: Thu Mar 31, 2011 6:46 pm

by cardoc » Thu Nov 10, 2011 10:44 pm

99,999^2 - 1^2 =

A. 10^10 - 2
B. (10^5 - 2)^2
C. 10^4(10^5 - 2)
D. 10^5(10^4 - 2)
E. 10^5(10^5 - 2)

Source: Beat The GMAT — Problem Solving | Thu Nov 10, 2011 10:44 pm

rijul007: Legendary Member; Posts: 588; Joined: Sun Oct 16, 2011 9:42 am; Location: New Delhi, India; Thanked: 130 times; Followed by:9 members; GMAT Score:720

by rijul007 » Thu Nov 10, 2011 10:54 pm

99,999^2 - 1^2

a^2 - b^2 = (a-b)(a+b)

(99999+1)(99999-1)
10^5(10^5-2)

Option E

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