应该是∂z/∂x吧!
令 u=x+y^2+z =>du/dx=1+dz/dx
u=lnu^(1/2)=1/2 *ln u
du/dx=1/2 * 1/u *du/dx
=>du/dx=u/(1/2+u)=1+dz/dx
=>dz/dx=u/(1/2+u)-1=1/(1+2u)=1/[1+2(x+y^2+z )]