Understanding derivitaves

1. Apr 4, 2008

Mol_Bolom

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.

2. Apr 4, 2008

Werg22

No, first and third are wrong.

1. 15x^4 + 6x^2 + 5
2. 60x^3 + 12x
3. 180x^2 + 12
4. 360x
5. 360

3. Apr 4, 2008

uman

The derivative of $$5x^2-2$$ is actually $$10x$$.

4. Apr 4, 2008

Mol_Bolom

Ah...That was the area I had a problem with...The final solitary number...

5. Apr 4, 2008

HallsofIvy

Staff Emeritus
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.

The first derivative is 15x4+ 6x2+ 5

Well, I wouldn't call it "final". That's the fourth derivative. The fifth derivative, and all succeeding derivatives is 0.

6. Apr 4, 2008

ice109

don't you mean the differential of y?

isn't the differential of x : dx?

7. Apr 5, 2008

sutupidmath

I don't see any
y's in there. It can be any variable expressed as a function of x.
I think this is what Halls said also!

8. Apr 5, 2008

woops