## anonymous 5 years ago how do u find the derivative of f(x) = 4x^3/4 -5x I got f'(x)=3/x^1/4 - 5 can I combine these to get one fraction

1. anonymous

$f \prime(x) = 3/x ^{1/4}-5$

2. anonymous

so then how would I find f''(x). Do I use the quotient rule

3. anonymous

Yes, you can use the quotient rule again. So $f \prime \prime(x) = -(3/4)x^{-5/4}$