Can someone refresh me on a rule or illustrate the logic that a negative number raised to any power still yields a negative answer?
examples:
-2^2 = -4
-2^5 = -32
-3^2 = -9
-3^3 = -27
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
Negative Number Raised to a Power
This topic has expert replies
-
BlindVision
.gif)
- Master | Next Rank: 500 Posts
- Posts: 253
- Joined: Fri Dec 26, 2008 8:39 pm
- Thanked: 8 times
- Followed by:1 members
-
Bhattu
- Junior | Next Rank: 30 Posts
- Posts: 21
- Joined: Thu Apr 05, 2007 4:58 am
- Thanked: 2 times
- GMAT Score:600
I think there was a typo, shouldn't it be = (negative integer) raised to (odd positive power) is negative?cramya wrote:(negative integer) raised to (even positive power) is positive.
-2 ^ 2 = 4 (not -4 as stated above)
-2 ^ 4 = 16
(negative integer) raised to (odd positive power) is positive.
-2^3 = -8
-2^1 = -2
Hope this helps.
GMAT/MBA Expert
-
Ian Stewart
- GMAT Instructor
- Posts: 2621
- Joined: Mon Jun 02, 2008 3:17 am
- Location: Montreal
- Thanked: 1090 times
- Followed by:355 members
- GMAT Score:780
Here, it really depends on how the expression is written. If you raise -2 to the power of 2, the answer is certainly positive 4. That is, if you have:cramya wrote:(negative integer) raised to (even positive power) is positive.
-2 ^ 2 = 4 (not -4 as stated above)
(-2)^2
that is equal to 4, because this is equal to (-2)*(-2). However, if the negative is not enclosed in brackets, as was written in the original post:
-2^2
then by order of operations (BEDMAS), we must raise 2 to the power 2 first, then take the negative of that. So, if there are no brackets,
-2^2 = -4
because this is equal to -(2)*(2).
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
ianstewartgmat.com
ianstewartgmat.com
-
BlindVision
- Master | Next Rank: 500 Posts
- Posts: 253
- Joined: Fri Dec 26, 2008 8:39 pm
- Thanked: 8 times
- Followed by:1 members
What does the "B" in "BEDMAS" stand for? "Brackets"? Thank you!Ian Stewart wrote:
then by order of operations (BEDMAS), we must raise 2 to the power 2 first, then take the negative of that. So, if there are no brackets,
-2^2 = -4
because this is equal to -(2)*(2).
GMAT/MBA Expert
-
Ian Stewart
- GMAT Instructor
- Posts: 2621
- Joined: Mon Jun 02, 2008 3:17 am
- Location: Montreal
- Thanked: 1090 times
- Followed by:355 members
- GMAT Score:780
Yes, 'brackets'. The mnemonic is sometimes presented as 'PEDMAS', where the P stands for 'parentheses'.BlindVision wrote:What does the "B" in "BEDMAS" stand for? "Brackets"? Thank you!Ian Stewart wrote:
then by order of operations (BEDMAS), we must raise 2 to the power 2 first, then take the negative of that. So, if there are no brackets,
-2^2 = -4
because this is equal to -(2)*(2).
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
ianstewartgmat.com
ianstewartgmat.com
