Just doing example questions to better understand. Find all first and second partial derivatives for the function

Question

Just doing example questions to better understand. Find all first and second partial derivatives for the function 
u= xy^2+x^2y

Damon · Answer

du/dx = y^2 + 2xy d^2u/dx^2 = 2y du/dy = 2xy + x^2 d^2u/dy^2 = 2x

Steve · Answer

Let's not forget d^2u/dx/dy = d^2u/dydx = 2

Drew · Answer

This is just for study for exam coming up and says it could be worth up to 12 marks. Not understanding vry well the two