Calculus problem, I don't understand what it means?

  • Thread starter dominus96
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  • #1
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Homework Statement



Dx(7x+2-3x5)

Homework Equations



CNXN-1?

The Attempt at a Solution



Basically, I am in Physics C and this is our first homework assignment dealing with calculus/derivatives. I was able to do some of them, but I have no idea how to do this one, mainly because I don't know what to do with the Dx.

To make sure I am on the right track, please tell me if this is the correct answer for another problem:

Problem: f(x) = -5x2+2x-1, find df/dx

And my answer is -10x + 2, using the power rule. Is that right?
 

Answers and Replies

  • #2
tiny-tim
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… power rules ok!

Hi dominus96! :smile:
To make sure I am on the right track, please tell me if this is the correct answer for another problem:

Problem: f(x) = -5x2+2x-1, find df/dx

And my answer is -10x + 2, using the power rule. Is that right?
Completely! :biggrin:
… mainly because I don't know what to do with the Dx.
Dx is just another way of writing d/dx.

Just use the power rule again … which, as you say, is:
CNXN-1
 
  • #3
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Thank you very much tiny-tim. If you don't mind, I have one more similar problem that is also written in a way I don't understand. Here it is:

Find f' for f(x) = 11x - 2.

Is f' (f prime) basically the first derivative again, or different?
 
  • #4
tiny-tim
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Find f' for f(x) = 11x - 2.

Is f' (f prime) basically the first derivative again, or different?
Yup … same thing! :biggrin:

(the advantage of the ' notation is that it's much easier to type f'' and f''' and so on! :smile:)
 
  • #5
HallsofIvy
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You should also remember that the derivative of a function, whether it is called "Dx f" or "df/dx" or "f' " is a generalization of the slope of a line- and since f(x)= 11x- 2 has a straight line as its graph, the derivative is ...
 

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