A math question about business calc

[redbox]

Well, guys I know there are alot of smart people on this forum so I figured you could help her out. :thumbsup:


Function: how to find derivative.

f(x)= 1
___
2x


f(x)= 1
___
6x squared


We are looking for the second derivative of these functions.

 

[Geocentricity]

wow.... I remember doing these in HS. Its so easy that I'm only going to tell you to Google it.

 

[randumb]

f(x)=2x
f'(x)=2
f''(x)=0

f(x)=6x^2
f'(x)=12x
f''(x)=12

 

[FleshLight]

f(x)= 1/2x = 2x^-1

Use power rule.

f(x) = 1/(6x^2) = 6x^-2

Use power rule.

 

[imported_quasi]

Originally posted by: FleshLight
f(x)= 1/2x = 2x^-1

Use power rule.

f(x) = 1/(6x^2) = 6x^-2

Use power rule.

Don't even need the power rule, you can just use the constant multiple rule.

 

[redbox]

The book has the answer x^-2 on the first question.

The other answer the book has as x^-4.

Could you show your work on how you got to your answers?

Thanks again guys.

 

[WombRaider]

http://en.wikipedia.org/wiki/Calculus_with_polynomials

good 'ol calculus. i hated doing optimization problems.

 

[hypn0tik]

For any n, if f(x) = x^n, f'(x) = nx^(n-1)

1) f(x) = 1/2 * x^-1
2) f(x) = 1/6 * x^-2

The constants out front don't change. When you apply the differentiation rule, you simply need to multiply by the constant in front.

For example, the first question:
f(x) = 1/2 * x^-1. In this case, n = -1 --> f'(x) = 1/2 * (-1) * x^-2 = -1/2 * x^-2. f"(x) = -1/2 * -2 * x^-3 = x^-3

 

[Cogman]

mathmatica is your friend. Everything hypn0tik said is right, just think of 1/x as x^-1 and derive from there.

 

[FleshLight]

Maybe he wants us to show it using the definition of derivative.