Verified answer

f(x) = √x + 1 / 3√x

f`(x)=(x^(1/2) + 1/3 * x^(-1/2))`=

        =1/(2sqrt{x}) +1/3 *(-1/2)*x^(-3/2)=

        =1/(2sqrt{x}) - 1/(6xsqrt{x})=

        =(3x-1)/(6xsqrt{x})