Calculus help! Derivative issue?

i took the derivative using logarithmic differentiation and had an issue. They manipulated 2/3(x^-1/3)+2/3(y^-1/3)(yprime) into (1/cubed root x)+(yprime/cubed root y). Can someone please explain this to me?

husoski2015-11-19T19:05:22Z

Favorite Answer

One of you is off by a factor of 2/3. The fact that x^(-1/3) = 1/cuberoot(x) explains the rest.

Nobody can tell without who's in error without seeing the problem.