Question

How do I derive this: f(x)=3lxl -x^(3)

Answer 1

just have to deal with x<0 , and x>0 separately

Answer 2

derivative undefined at x=0

Answer 3

|f(x)| = f'(x) * f(x)/|f(x)|

Answer 4

cool ... that works

Answer 5

yes, yes it does :)

Answer 6

\[
\large \frac{d}{dx}|f(x)| = \frac{f'(x)f(x)}{|f(x)|}
\]

Answer 7

3-3x^2, when x>0 and -3-3x^2 when x<0. Not differentiable at x=0

Answer 8

so: 3x\|x| - 3x^2 yes

Answer 9

and then would the second derivative be differentiable everywhere?
-6x