# Thread: [SOLVED] Find first and second derivative.

1. ## [SOLVED] Find first and second derivative.

$f(x) = 2x^2+\frac{8}{x^2}$

$f'(x) = 4x +16x^{-1} => 4x+\frac{16}{x}$

$f''(x) = 4 -16$

Is that right?

2. Hi el123!

Originally Posted by el123
$f(x) = 2x^2+\frac{8}{x^2}$

$f'(x) = 4x +16x^{-1} => 4x+\frac{16}{x}$
No, that is not correct. You tried to integrate or something.

If
$g(x) := 8*\frac{1}{x^2} = 8*x^{-2}$

then

$g'(x) = -2*8*x^{-2-1} =-2*8*x^{-3} = -16*\frac{1}{x^3}$

Thus $f'(x) = 4x -16*\frac{1}{x^3}$

Do you think you find the second derivative on your own?

Yours
Rapha

3. is it $f''(x) = 4 +48x^{-4}$?

4. Hello.

Originally Posted by el123
is it $f''(x) = 4 +48x^{-4}$?
That is correct.

$f''(x) = 4 +48x^{-4} = 4 + \frac{48}{x^4}$

Rapha

5. Cheers mate.