Find the second derivative of this function?

Question

18 divided by the cubed root of x.

I tried doing this: the derivative is -12x^(-2/3), which would make the second derivative 20x^(-8/3)

but it s saying my answer is incorrect. What am I doing wrong?

Answer 1

Step 1 :

The function is .

Differentiate with respect to x.

Step 2 :

Differentiate with respect to x.

Solution :