I just took an official CAT with a pretty good outcome... but I don't know why I got the FIRST freakin question wrong.... i did 75 times and still can't get to the right answer...
(2^(4-1)^2)/(2^(3-2)
OA: [spoiler]2^8[/spoiler]
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
help...
This topic has expert replies
GMAT/MBA Expert
-
Rahul@gurome
- GMAT Instructor
- Posts: 1179
- Joined: Sun Apr 11, 2010 9:07 pm
- Location: Milpitas, CA
- Thanked: 447 times
- Followed by:88 members
(2^(4-1)^2)/(2^(3-2) = (2^3^2)/(2^1) = (2^9)/2 = 2^(9-1) = 2^8shibal wrote:I just took an official CAT with a pretty good outcome... but I don't know why I got the FIRST freakin question wrong.... i did 75 times and still can't get to the right answer...
(2^(4-1)^2)/(2^(3-2)
OA: [spoiler]2^8[/spoiler]
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
-
shibal
- Master | Next Rank: 500 Posts
- Posts: 345
- Joined: Wed Mar 18, 2009 6:53 pm
- Location: Sao Paulo-Brazil
- Thanked: 12 times
- GMAT Score:660
but by exponent rules (2^3)^2 be 2^(3*2)???Rahul@gurome wrote:(2^(4-1)^2)/(2^(3-2) = (2^3^2)/(2^1) = (2^9)/2 = 2^(9-1) = 2^8shibal wrote:I just took an official CAT with a pretty good outcome... but I don't know why I got the FIRST freakin question wrong.... i did 75 times and still can't get to the right answer...
(2^(4-1)^2)/(2^(3-2)
OA: [spoiler]2^8[/spoiler]
GMAT/MBA Expert
-
Rahul@gurome
- GMAT Instructor
- Posts: 1179
- Joined: Sun Apr 11, 2010 9:07 pm
- Location: Milpitas, CA
- Thanked: 447 times
- Followed by:88 members
The question is (2^(4-1)^2)/(2^(3-2)shibal wrote:
but by exponent rules (2^3)^2 be 2^(3*2)???
Numerator = (2^(4-1)^2) = 2^3^2
3^2 = 9, so numerator reduces to 2^9
Now denominator = 2^(3-2) = 2^1 = 2
Therefore, 2^9/2 = 2^(9-1) = 2^8
We cannot write (2^3)^2 = 2^(3*2), as 2^3^2 = 2^(3^2) = 2^9
2^3^2 means 2 is a power of 3, which is again a power of 2, so first solve 3^2 = 9 and then the expression reduces to 2^9.
Does that help?
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
-
shibal
- Master | Next Rank: 500 Posts
- Posts: 345
- Joined: Wed Mar 18, 2009 6:53 pm
- Location: Sao Paulo-Brazil
- Thanked: 12 times
- GMAT Score:660
Rahul@gurome wrote:The question is (2^(4-1)^2)/(2^(3-2)shibal wrote:
but by exponent rules (2^3)^2 be 2^(3*2)???
Numerator = (2^(4-1)^2) = 2^3^2
3^2 = 9, so numerator reduces to 2^9
Now denominator = 2^(3-2) = 2^1 = 2
Therefore, 2^9/2 = 2^(9-1) = 2^8
We cannot write (2^3)^2 = 2^(3*2), as 2^3^2 = 2^(3^2) = 2^9
2^3^2 means 2 is a power of 3, which is again a power of 2, so first solve 3^2 = 9 and then the expression reduces to 2^9.
Does that help?
hummm so can I conclude that (2^3)^2 is different from (2^3^2)?
GMAT/MBA Expert
-
Rahul@gurome
- GMAT Instructor
- Posts: 1179
- Joined: Sun Apr 11, 2010 9:07 pm
- Location: Milpitas, CA
- Thanked: 447 times
- Followed by:88 members
Yes definitely, they are different.shibal wrote:
hummm so can I conclude that (2^3)^2 is different from (2^3^2)?
2^3 = 8 so (2^3)^2 = 8^2 = 64
and 2^3^2 = 2^(3^2) = 2^9
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
