Wednesday 17 March 2010

Negative Exponents

Negative exponents have nothing to do with negative numbers.

If we think of the use of negative exponents in Scientific Notation we can understand them a bit better.



A negative exponent with a power of 10 means it is a decimal.




10 to the -3 = 0.001, which we can also write as 1 over 1000.





When we use powers of 10 in Scientific Notation we are changing the negative power to a decimal and multiplying it by the significant digits.




Significant digits = 2.63

10 to -3 = 0.001

Multiply and you have 0.00263









A negative exponent means "the reciprocal"


2 to the -3 can be rewritten as 1 over 2 to the 3rd (or 2 cubed).

2 cubed is 8.

Our final answer is one over eight.





When we are simplifying a more complex problem that includes a negative exponent we:





reduce any fractions

combine the exponets for each base:

x
and
y








Finally put any negative exponents in the opposite area of the fraction:


If there is a negative in the numerartor -> put it in the denominator.

If there is a negative in the denominator -> put it in the numerator.

Your final answer should never include a negative exponent.

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