SOLUTION: please help me simlify this problem:{{{r^9(r^-5)/r^-2(r^-7)}}}

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Question 597479: please help me simlify this problem:r%5E9%28r%5E-5%29%2Fr%5E-2%28r%5E-7%29
Answer by math-vortex(648) About Me  (Show Source):
You can put this solution on YOUR website!
Hi, there--
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Simplify
r%5E9%28r%5E-5%29%2Fr%5E-2%28r%5E-7%29
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When you multiply exponential expressions, you add their exponents: (r^9)(r^-5)=r^4 because 9+(-5)=4. Likewise, (r^-2)(r^-7)=r^-9
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r%5E9%28r%5E-5%29%2Fr%5E-2%28r%5E-7%29=r%5E4%2Fr%5E-9
When you divide exponential expressions you subtract there exponents: r^4/r^-9=r^13 because 4-(-9)=13.
r%5E4%2Fr%5E-9=r%5E13
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That's it!
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Feel free to email me via gmail if you have questions about this.
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Ms.Figgy
math.in.the.vortex@gmail.com