derivatives of a function

Question

find the derivative of

f(x)= (x^2 -sqrt(x))*3x

im pretty sure you use the product rule of derivatives, but I cant seem to get the right answer.

Answer 1

f(x) = (x² - √x)(3x)

Distribute the 3x to get f(x) = 3x³ - 3x^3/2

So, f'(x) = 9x² - (9/2)√x