I was able to guess the correct answer but can anyone please explain the answer in detail.
If 2^x - 2^x-2 = 3(2^13) then what is value of x?
a. 9
b. 11
c. 13
d. 15
e. 17
OA
d
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
algebric equation
This topic has expert replies
-
DanaJ
- Site Admin
- Posts: 2567
- Joined: Thu Jan 01, 2009 10:05 am
- Thanked: 712 times
- Followed by:550 members
- GMAT Score:770
It's only a matter of seeing the common factor of 2^x and 2^(x-2). It will be 2^(x-2):
2^x - 2^(x-2) = 2^(x-2)*(2^2 - 1) = 2^(x-2)*3
Since you have 2^(x - 2)*3 = 3*2^13, you get that x - 2 = 13, with x = 15.
2^x - 2^(x-2) = 2^(x-2)*(2^2 - 1) = 2^(x-2)*3
Since you have 2^(x - 2)*3 = 3*2^13, you get that x - 2 = 13, with x = 15.
