Exponents

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relaxin99: Senior | Next Rank: 100 Posts; Posts: 73; Joined: Tue Sep 16, 2008 4:33 pm; Thanked: 2 times

by relaxin99 » Mon Feb 23, 2009 1:27 pm

2^x - 2^ (x-2) = 3(2^13), what is the value of x?

9
11
13
15
17

Source: Beat The GMAT — Problem Solving | Mon Feb 23, 2009 1:27 pm

x2suresh: Master | Next Rank: 500 Posts; Posts: 258; Joined: Thu Aug 07, 2008 5:32 am; Thanked: 16 times

by x2suresh » Mon Feb 23, 2009 2:27 pm

relaxin99 wrote:2^x - 2^ (x-2) = 3(2^13), what is the value of x?

9
11
13
15
17

2^x - 2^ (x-2) = 3(2^13)

2^(x-2) (2^2-1) =3* 2^13

2^(x-2) *3 = 3* 2^13

x-2=13 --> x=15

relaxin99: Senior | Next Rank: 100 Posts; Posts: 73; Joined: Tue Sep 16, 2008 4:33 pm; Thanked: 2 times

by relaxin99 » Mon Feb 23, 2009 2:57 pm

Great explanation, exponents are my weakness for sure

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