x is:

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sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Fri Apr 03, 2009 3:39 am

In the equation 2 ^ (x + 5) = 2 ^ (x + 3) + 6, the value of x is:
A. 2
B. 3
C. -4
D. 4
E. -2

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Source: Beat The GMAT — Problem Solving | Fri Apr 03, 2009 3:39 am

scoobydooby: Legendary Member; Posts: 1035; Joined: Wed Aug 27, 2008 10:56 pmFollowed by: 1 member; Thanked: 104 times

by scoobydooby » Fri Apr 03, 2009 4:02 am

2 ^ (x + 5) = 2 ^ (x + 3) + 6

=>2 ^ (x + 5)-2 ^ (x + 3)=6
=>2^(x+3){(2^2)-1}=6
=>2^(x+3)=6/3=2
equating the powers on both sides,

x+3=1
=>x=-2
hence, E

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