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March 29, 2024, 03:03:26 am

Author Topic: Help with Derivatives  (Read 4825 times)  Share 

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Dragomistress

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Re: Help with Derivatives
« Reply #15 on: February 15, 2017, 04:07:51 pm »
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So what does the d/dx mean?

Or is the same as dy/dx?

RuiAce

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Re: Help with Derivatives
« Reply #16 on: February 15, 2017, 04:13:07 pm »
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So what does the d/dx mean?

Or is the same as dy/dx?



Dragomistress

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Re: Help with Derivatives
« Reply #17 on: February 15, 2017, 04:37:07 pm »
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So I use the d/dy when there is no designated letter for a value for convenience?

For example solve the derivative of: (3x+4)^3

d/dx (3x+4)^3 = 9x(3x+4)^2

Instead of writing
Let y = (3x+4)^3

dy/dx = (3x+4)^3
          = 9x(3x+4)^2

jakesilove

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Re: Help with Derivatives
« Reply #18 on: February 15, 2017, 04:51:54 pm »
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So I use the d/dy when there is no designated letter for a value for convenience?

For example solve the derivative of: (3x+4)^3

d/dx (3x+4)^3 = 9x(3x+4)^2

Instead of writing
Let y = (3x+4)^3

dy/dx = (3x+4)^3
          = 9x(3x+4)^2

Yep that's perfect!
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Dragomistress

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Re: Help with Derivatives
« Reply #19 on: February 15, 2017, 06:14:53 pm »
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Now I just feel like I am abusing the forum for questions :/ but I just truly don't understand.


How do I do this using the quick formula?

jakesilove

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Re: Help with Derivatives
« Reply #20 on: February 15, 2017, 06:35:54 pm »
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Now I just feel like I am abusing the forum for questions :/ but I just truly don't understand.


How do I do this using the quick formula?

The quick formula you are looking for here is the chain rule. It goes like this.



So, here's what I want you to do. Write each question out in your work book. Identify f(x), and write it out. For instance, in a), f(x)=3x+7. Then, find f'(x) (ie. the first derivative of f(x)). Write out f'(x). For instance, in a), f'(x)=3. Then, plug the values you've found into the formula above! That's all there is to it.
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jamonwindeyer

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Re: Help with Derivatives
« Reply #21 on: February 16, 2017, 12:53:24 am »
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Now I just feel like I am abusing the forum for questions :/

You could never! If you are benefitting from the help then our time is well spent - It's what we are here for ;D