Remember how powers are defined. 2^3 = 2*2*2. So, a nice feature of exponents is that multiplying numbers adds the exponents = for instance, 2^3*2^4 = (2*2*2)*(2*2*2*2) = 2^(3 + 4) = 2^7
Now, lets say you have the problem 2^7*2^x = 2^4. How would you solve this? By the nice exponent property above, this is the same as 7 + x = 4, so x = -3. But expanding these out, 2^7 = 128, 2^4 = 16, so 2^-3 should be 1/8.
This is also why anything (except 0) to the 0th power is 1:
a^x*a^0 = a^(x + 0) = a^x, so a^0 = 1
2006-11-21 02:31:43
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answer #1
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answered by sofarsogood 5
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3 to the negative 2 is 1/9. 3 to the 2nd is 3*3. The negative means that it is in the denominator.
2006-11-21 10:32:08
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answer #2
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answered by GOPneedsarealconservative 4
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They can be negative, when the exponential expression is in the denominator.
Ex. 3 ^ (-2) = 1/ (3^2)
Note: Definition of Negative Exponents
If a is a nonzero real number and n is a positive integer, then
a ^(-n) = 1/(a^n)
2006-11-21 11:32:43
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answer #3
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answered by S. B. 6
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I don't think you mean "why can't powers be negative", but rather "why can't the result of raising something to a power, be negative"?
well, it can
take (-3)^3 = -27, a negative number.
now if you specifically what that something raised to the power of 2, gives you a negative number, then you need to use Complex numbers.
the simplest Complex numbers would be an Imaginary number, such as 'i', which by definition, is the square root of 1.
so i^2=-1
complex numbers are typically part of studies of a bit more advanced math, typically done in college.
hope this helps a bit
2006-11-21 12:29:27
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answer #4
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answered by AntoineBachmann 5
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if the power is negative, get the reciprocal of the base and make the exponent positive
in your example, 3 to the power of -2 is equal to 1 over 3 to the power of 2, or 1/9
2006-11-21 10:34:05
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answer #5
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answered by mawi 2
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3^-2 = 1/3^2=1/9=.1111111111111
2006-11-21 10:26:02
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answer #6
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answered by bonkified_fl 2
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Reverse the process..
The square root of -9 is 3i, where the i stands for imaginary number. This is a whole different number system.
2006-11-21 10:43:37
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answer #7
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answered by The Cheminator 5
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by definition 3^-2 = 1/(3^2)
You can't argue with a definition.
2006-11-21 10:31:55
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answer #8
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answered by Jack 2
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Powers can be negative.
2006-11-21 10:41:24
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answer #9
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answered by Anonymous
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