VIC problem

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sawaan6789: Newbie | Next Rank: 10 Posts; Posts: 3; Joined: Sat Oct 24, 2009 6:00 am

by sawaan6789 » Sat Oct 24, 2009 5:53 pm

If XY =1, What is value of 2^(x+y)^2/2^(x-y)^2?

Please help[/img]

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Source: Beat The GMAT — Problem Solving | Sat Oct 24, 2009 5:53 pm

truplayer256: Master | Next Rank: 500 Posts; Posts: 392; Joined: Thu Jan 15, 2009 12:52 pm; Location: New Jersey; Thanked: 76 times

by truplayer256 » Sat Oct 24, 2009 6:01 pm

(x+y)^(2)=x^2+2xy+y^2

(x-y)^(2)=x^2-2xy+y^2

(x+y)^(2)-(x-y)^(2)=2xy+2xy=4xy

2^(x+y)^(2)/2^(x-y)^(2)=2^[(x+y)^(2)-(x-y)^(2)]=2^4xy

xy=1

2^4=16

Leon1984: Senior | Next Rank: 100 Posts; Posts: 32; Joined: Sun Oct 18, 2009 5:23 pm; Location: Israel; Thanked: 3 times; GMAT Score:640