How do you find derivatives and what do they represent in calculus?

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Discussion Overview

The discussion revolves around the concept of derivatives in calculus, including their calculation and interpretation. Participants explore various examples of derivatives, including polynomials, and clarify the distinction between derivatives and differentials.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants present calculations for the derivatives of functions, such as the first and second derivatives of polynomials.
  • There are claims regarding the derivatives of specific functions, with some participants asserting that the derivative of 5x^2 - 2 is 10, while others argue it is 10x.
  • One participant suggests that the final derivative of a polynomial is not simply a solitary number, but rather that the fifth and all succeeding derivatives are zero.
  • Clarifications are made regarding the terminology, distinguishing between the derivative and the differential of functions.
  • Some participants express uncertainty about their understanding of derivatives and differentials, indicating a learning process.

Areas of Agreement / Disagreement

Participants express differing views on the correct derivatives of certain functions, particularly regarding the function 5x^2 - 2. There is no consensus on the correct interpretation of derivatives versus differentials, and some participants challenge each other's calculations.

Contextual Notes

Some participants' claims about derivatives contain errors, and there are unresolved issues regarding the definitions and calculations presented. The discussion includes multiple interpretations and assumptions that are not fully clarified.

Mol_Bolom
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I think I finally figured out derivitaves, but not sure...

The derivative/differential of x in
x is 1
3x + 5 is 3
5x^2 - 2 is 10

And breaking down a quadratic thus

3x^5 + 2x^3 + 5x - 1
The first derivative is 15x^4 + 6x^2
The second derivative is 60x^3 + 12x
Third 180x^2
Fourth 360x
And final 360.
 
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Mol_Bolom said:
3x^5 + 2x^3 + 5x - 1
The first derivative is 15x^4 + 6x^2
The second derivative is 60x^3 + 12x
Third 180x^2
Fourth 360x
And final 360.

No, first and third are wrong.

1. 15x^4 + 6x^2 + 5
2. 60x^3 + 12x
3. 180x^2 + 12
4. 360x
5. 360
 
The derivative of [tex]5x^2-2[/tex] is actually [tex]10x[/tex].
 
Ah...That was the area I had a problem with...The final solitary number...
Wado (thanks)
 
Mol_Bolom said:
I think I finally figured out derivitaves, but not sure...

The derivative/differential of x in
x is 1
3x + 5 is 3
5x^2 - 2 is 10
The derivative (not differential) of 5x2- 2 at at x= 1 is 10. More generally, the derivative of 5x2- 2 at any x is 10x. The differential of x is dx, the differential fo 3x+ 5 is 3dx and the differential of 5x2- 2 is 10x dx.

And breaking down a quadratic thus

3x^5 + 2x^3 + 5x - 1
The first derivative is 15x^4 + 6x^2
The first derivative is 15x4+ 6x2+ 5

The second derivative is 60x^3 + 12x
Third 180x^2
Fourth 360x
And final 360.
Well, I wouldn't call it "final". That's the fourth derivative. The fifth derivative, and all succeeding derivatives is 0.
 
HallsofIvy said:
The derivative (not differential) of 5x2- 2 at at x= 1 is 10. More generally, the derivative of 5x2- 2 at any x is 10x. The differential of x is dx, the differential fo 3x+ 5 is 3dx and the differential of 5x2- 2 is 10x dx.

don't you mean the differential of y?

isn't the differential of x : dx?
 
ice109 said:
don't you mean the differential of y?
I don't see any
y's in there. It can be any variable expressed as a function of x.
ice109 said:
isn't the differential of x : dx?
I think this is what Halls said also!
 
woops
 

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