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October 21st, 2009, 01:33 PM   #1
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Chain Rule QUestion

I have a question in regards to one of the chain rules for finding the dirivative of a composite functions,

my question is on the logarithmic rule that follows,

y = log(base7)x
y = logx/log7
y = 1/log7 * logx

[color=#BF0000]y(primed) = 1/log7 * 1/x[/color]
y(primed) = 1/x(log7)

Now in red is 1/log7 being treated as a constant or coefficient? Weren't they suppose to us the product rule for finding a derivative?
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October 21st, 2009, 03:13 PM   #2
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Re: Chain Rule QUestion

The value does not depend on x, so it is treated as a constant coefficient. You can treat it with the product rule without getting the wrong result since

so the distinction is of interest for practical reasons, not because they'll yield different answers.
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October 21st, 2009, 09:01 PM   #3
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Re: Chain Rule QUestion

Hmm that's odd I posted a reply earlier at school and it didn't go through....

Well anywas thanks for clarifying things up cmusik, but another quick questions....

Why is d/dx of [color=#BF0000]e^(-x)[/color] = [color=#BF0000]-e^(-x)[/color]? Shouldn't it just be [color=#BF0000]e^(-x)[/color]?
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October 21st, 2009, 09:09 PM   #4
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Re: Chain Rule QUestion

The chain rule applies here:
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October 21st, 2009, 10:33 PM   #5
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Re: Chain Rule QUestion

I get it now, thanks.
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