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

  • Context: High School 
  • Thread starter Thread starter Mol_Bolom
  • Start date Start date
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
7 replies · 3K views
Mol_Bolom
Messages
24
Reaction score
0
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.
 
Physics news on Phys.org
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!