SOLUTION: how can i simplify and write with positive exponents only? (b^2)^-6 over b^-4

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Question 75556: how can i simplify and write with positive exponents only?
(b^2)^-6
over
b^-4

Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
.
%28b%5E2%29%5E%28-6%29%2Fb%5E%28-4%29
.
First, we'll convert this to have only positive exponents, and then we'll simplify.
.
Let's get the numerator to have a positive exponent. Begin by using the power rule for
exponents. This rule says that if you have a term with an exponent that is then raised
to another exponent, you multiply the two exponents. So:
.
%28b%5E2%29%5E%28-6%29 becomes b%5E%282%2A%28-6%29%29+=+b%5E%28-12%29. But a base raised to a negative
number is equal to that same base to a positive number and then divided into 1. So the
numerator b%5E%28-12%29 becomes 1 divided by b%5E%2812%29 which is written as:
.
1%2F%28b%5E12%29
.
Now work on the denominator. %28b%29%5E%28-4%29 just falls under the rule to divide 1 by the
same base with a positive exponent. So the denominator becomes:
.
1%2F%28b%5E%284%29%29
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Now putting the numerator and denominator together you get:
.
%281%2F%28b%5E12%29%29%2F%281%2F%28b%5E%284%29%29%29
.
Now recall that a long time ago you learned that when you divide by a fraction, you invert
the divisor and multiply the dividend by it. When you set that up, you get:
.
%281%2F%28b%5E12%29%29%2A%28%28b%5E4%29%2F1%29
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When you multiply the numerators and denominators of both these terms you get:
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%281%2Ab%5E4%29%2F%28%28b%5E12%29%2A1%29
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which simplifies to:
.
b%5E4%2Fb%5E12
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and you perform this division by subtracting the exponent in the denominator from the
exponent in the numerator to get: b%5E%284-12%29+=+b%5E-8. But there is a negative exponent
and the problem calls for all positive exponents. So just divide the base with a
positive exponent into 1 to get: 1%2Fb%5E8 and that is your answer.
.
Hope this helps you to understand the workings of negative exponents.