Hi,
I thought I was correct but the answer was 15. Can you please help?
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
prep question
This topic has expert replies
-
Neo2000
- Legendary Member
- Posts: 519
- Joined: Sat Jan 27, 2007 7:56 am
- Location: India
- Thanked: 31 times
Always think about checking your work by substituting the answer you got back into the question
In any case
taking 2^(X-2) common you get
2^(X-2)[2^2 -1] = 3(2^13)
2^(X-2)[3] = 3(2^13)
Thus you can see that 2^(X-2)=(2^13)
OR X-2 = 13
X = 15
In any case
taking 2^(X-2) common you get
2^(X-2)[2^2 -1] = 3(2^13)
2^(X-2)[3] = 3(2^13)
Thus you can see that 2^(X-2)=(2^13)
OR X-2 = 13
X = 15
-
Cybermusings
- Legendary Member
- Posts: 559
- Joined: Tue Mar 27, 2007 1:29 am
- Thanked: 5 times
- Followed by:2 members
2^x - 2^(x-2) = 3 (2^13)
Take 2^(x-2) common here
2^(x-2)*[2^2 - 1] = 3(2^13)
2^(x-2)*[4-1]= 3(2^13)
2^(x-2)*[3]= 3(2^13)
2^(x-2)=2^13
Or x-2=13
Thus x = 15(base of the two powers are the same so equate the powers)
Take 2^(x-2) common here
2^(x-2)*[2^2 - 1] = 3(2^13)
2^(x-2)*[4-1]= 3(2^13)
2^(x-2)*[3]= 3(2^13)
2^(x-2)=2^13
Or x-2=13
Thus x = 15(base of the two powers are the same so equate the powers)
